20656616640 has 336 divisors, whose sum is σ = 73033981440. Its totient is φ = 4942080000.

The previous prime is 20656616633. The next prime is 20656616693. The reversal of 20656616640 is 4661665602.

It is a happy number.

It is a super-2 number, since 2×20656616640² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20656616592 and 20656616601.

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, 9175515 + ... + 9177765.

It is an arithmetic number, because the mean of its divisors is an integer number (217363040).

Almost surely, 2^20656616640 is an apocalyptic number.

20656616640 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 20656616640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36516990720).

20656616640 is an abundant number, since it is smaller than the sum of its proper divisors (52377364800).

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

20656616640 is a wasteful number, since it uses less digits than its factorization.

20656616640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2372 (or 2351 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 42.

The spelling of 20656616640 in words is "twenty billion, six hundred fifty-six million, six hundred sixteen thousand, six hundred forty".