31381136640 has 1296 divisors, whose sum is σ = 137404874880. Its totient is φ = 6827950080.

The previous prime is 31381136629. The next prime is 31381136641. The reversal of 31381136640 is 4663118313.

31381136640 is a `hidden beast` number, since 3 + 1 + 3 + 8 + 1 + 1 + 3 + 6 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (1296).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 31381136595 and 31381136604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31381136641) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 441987805 + ... + 441987875.

It is an arithmetic number, because the mean of its divisors is an integer number (106022280).

Almost surely, 2^31381136640 is an apocalyptic number.

31381136640 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31381136640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (68702437440).

31381136640 is an abundant number, since it is smaller than the sum of its proper divisors (106023738240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31381136640 is an equidigital number, since it uses as much as digits as its factorization.

31381136640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

31381136640 divided by its product of nonzero digits (31104) gives a triangular number (1008910 = T₁₄₂₀).

The spelling of 31381136640 in words is "thirty-one billion, three hundred eighty-one million, one hundred thirty-six thousand, six hundred forty".