21507661711656 has 48 divisors (see below), whose sum is σ = 58285719492000. Its totient is φ = 7164814126752.

The previous prime is 21507661711651. The next prime is 21507661711681. The reversal of 21507661711656 is 65611716670512.

21507661711656 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 7 + 6 + 617 + 1 + 16 + 5 + 6 = 666.

It is not an unprimeable number, because it can be changed into a prime (21507661711651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 91682956 + ... + 91917243.

It is an arithmetic number, because the mean of its divisors is an integer number (1214285822750).

Almost surely, 2^{21507661711656} is an apocalyptic number.

It is an amenable number.

21507661711656 is an abundant number, since it is smaller than the sum of its proper divisors (36778057780344).

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

21507661711656 is a wasteful number, since it uses less digits than its factorization.

21507661711656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183601838 (or 183601831 counting only the distinct ones).

The product of its (nonzero) digits is 3175200, while the sum is 54.

The spelling of 21507661711656 in words is "twenty-one trillion, five hundred seven billion, six hundred sixty-one million, seven hundred eleven thousand, six hundred fifty-six".