21661054406452 has 12 divisors (see below), whose sum is σ = 37976913320836. Its totient is φ = 10810507743360.

The previous prime is 21661054406447. The next prime is 21661054406477. The reversal of 21661054406452 is 25460445016612.

It can be written as a sum of positive squares in 2 ways, for example, as 17560575205156 + 4100479201296 = 4190534^2 + 2024964^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5004862533 + ... + 5004866860.

Almost surely, 2^{21661054406452} is an apocalyptic number.

It is an amenable number.

21661054406452 is a deficient number, since it is larger than the sum of its proper divisors (16315858914384).

21661054406452 is a wasteful number, since it uses less digits than its factorization.

21661054406452 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10009729938 (or 10009729936 counting only the distinct ones).

The product of its (nonzero) digits is 1382400, while the sum is 46.

The spelling of 21661054406452 in words is "twenty-one trillion, six hundred sixty-one billion, fifty-four million, four hundred six thousand, four hundred fifty-two".