31381020 has 144 divisors (see below), whose sum is σ = 107872128. Its totient is φ = 7594560.

The previous prime is 31380983. The next prime is 31381043. The reversal of 31381020 is 2018313.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 31380984 and 31381002.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 53167 + ... + 53753.

It is an arithmetic number, because the mean of its divisors is an integer number (749112).

Almost surely, 2^31381020 is an apocalyptic number.

31381020 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 31381020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (53936064).

31381020 is an abundant number, since it is smaller than the sum of its proper divisors (76491108).

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

31381020 is a wasteful number, since it uses less digits than its factorization.

31381020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622 (or 608 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 31381020 is about 5601.8764713264. The cubic root of 31381020 is about 315.4198483191.

Adding to 31381020 its reverse (2018313), we get a palindrome (33399333).

The spelling of 31381020 in words is "thirty-one million, three hundred eighty-one thousand, twenty".