20640147840 has 896 divisors, whose sum is σ = 82597747680. Its totient is φ = 4897013760.

The previous prime is 20640147833. The next prime is 20640147893. The reversal of 20640147840 is 4874104602.

20640147840 is a `hidden beast` number, since 2 + 0 + 640 + 1 + 4 + 7 + 8 + 4 + 0 = 666.

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 = 20640147795 and 20640147804.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 248676439 + ... + 248676521.

Almost surely, 2^20640147840 is an apocalyptic number.

20640147840 is a gapful number since it is divisible by the number (20) 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 20640147840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41298873840).

20640147840 is an abundant number, since it is smaller than the sum of its proper divisors (61957599840).

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

20640147840 is an equidigital number, since it uses as much as digits as its factorization.

20640147840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 36.

The spelling of 20640147840 in words is "twenty billion, six hundred forty million, one hundred forty-seven thousand, eight hundred forty".