21221552001656 has 16 divisors (see below), whose sum is σ = 39791001297600. Its totient is φ = 10610618322304.

The previous prime is 21221552001623. The next prime is 21221552001677. The reversal of 21221552001656 is 65610025512212.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 19136840 + ... + 20215383.

It is an arithmetic number, because the mean of its divisors is an integer number (2486937581100).

Almost surely, 2^{21221552001656} is an apocalyptic number.

It is an amenable number.

21221552001656 is a deficient number, since it is larger than the sum of its proper divisors (18569449295944).

21221552001656 is a wasteful number, since it uses less digits than its factorization.

21221552001656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39419638 (or 39419634 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 38.

Adding to 21221552001656 its reverse (65610025512212), we get a palindrome (86831577513868).

The spelling of 21221552001656 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred fifty-two million, one thousand, six hundred fifty-six".