21221556664552 has 16 divisors (see below), whose sum is σ = 39842705772900. Its totient is φ = 10596835125120.

The previous prime is 21221556664541. The next prime is 21221556664559. The reversal of 21221556664552 is 25546665512212.

It can be written as a sum of positive squares in 2 ways, for example, as 19413946327876 + 1807610336676 = 4406126^2 + 1344474^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21221556664552.

It is not an unprimeable number, because it can be changed into a prime (21221556664559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1742894427 + ... + 1742906602.

Almost surely, 2^{21221556664552} is an apocalyptic number.

It is an amenable number.

21221556664552 is a deficient number, since it is larger than the sum of its proper divisors (18621149108348).

21221556664552 is a wasteful number, since it uses less digits than its factorization.

21221556664552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3485801796 (or 3485801792 counting only the distinct ones).

The product of its digits is 8640000, while the sum is 52.

The spelling of 21221556664552 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred fifty-six million, six hundred sixty-four thousand, five hundred fifty-two".