21656021545 has 16 divisors (see below), whose sum is σ = 26357541120. Its totient is φ = 17078630400.

The previous prime is 21656021539. The next prime is 21656021603. The reversal of 21656021545 is 54512065612.

It is a de Polignac number, because none of the positive numbers 2^k-21656021545 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 210430 + ... + 295960.

It is an arithmetic number, because the mean of its divisors is an integer number (1647346320).

Almost surely, 2^21656021545 is an apocalyptic number.

It is an amenable number.

21656021545 is a deficient number, since it is larger than the sum of its proper divisors (4701519575).

21656021545 is an equidigital number, since it uses as much as digits as its factorization.

21656021545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86256.

The product of its (nonzero) digits is 72000, while the sum is 37.

The spelling of 21656021545 in words is "twenty-one billion, six hundred fifty-six million, twenty-one thousand, five hundred forty-five".