21507535818556 has 12 divisors (see below), whose sum is σ = 37639100832480. Its totient is φ = 10753507009280.

The previous prime is 21507535818551. The next prime is 21507535818661. The reversal of 21507535818556 is 65581853570512.

It is a junction number, because it is equal to n+sod(n) for n = 21507535818494 and 21507535818503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507535818551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65039461 + ... + 65369308.

It is an arithmetic number, because the mean of its divisors is an integer number (3136591736040).

Almost surely, 2^{21507535818556} is an apocalyptic number.

It is an amenable number.

21507535818556 is a deficient number, since it is larger than the sum of its proper divisors (16131565013924).

21507535818556 is a wasteful number, since it uses less digits than its factorization.

21507535818556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130450004 (or 130450002 counting only the distinct ones).

The product of its (nonzero) digits is 50400000, while the sum is 61.

The spelling of 21507535818556 in words is "twenty-one trillion, five hundred seven billion, five hundred thirty-five million, eight hundred eighteen thousand, five hundred fifty-six".