21621343566772 has 24 divisors (see below), whose sum is σ = 40096772561160. Its totient is φ = 10183307312640.

The previous prime is 21621343566751. The next prime is 21621343566839. The reversal of 21621343566772 is 27766534312612.

It can be written as a sum of positive squares in 4 ways, for example, as 2805185296 + 21618538381476 = 52964^2 + 4649574^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2273054913 + ... + 2273064424.

It is an arithmetic number, because the mean of its divisors is an integer number (1670698856715).

Almost surely, 2^{21621343566772} is an apocalyptic number.

It is an amenable number.

21621343566772 is a deficient number, since it is larger than the sum of its proper divisors (18475428994388).

21621343566772 is a wasteful number, since it uses less digits than its factorization.

21621343566772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4546119411 (or 4546119409 counting only the distinct ones).

The product of its digits is 15240960, while the sum is 55.

The spelling of 21621343566772 in words is "twenty-one trillion, six hundred twenty-one billion, three hundred forty-three million, five hundred sixty-six thousand, seven hundred seventy-two".