21621566454156 has 72 divisors (see below), whose sum is σ = 54912457257840. Its totient is φ = 7173194351616.

The previous prime is 21621566454149. The next prime is 21621566454167. The reversal of 21621566454156 is 65145466512612.

It is a happy number.

21621566454156 is a `hidden beast` number, since 2 + 1 + 6 + 21 + 566 + 4 + 5 + 4 + 1 + 56 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25811700 + ... + 26636196.

It is an arithmetic number, because the mean of its divisors is an integer number (762673017470).

Almost surely, 2^{21621566454156} is an apocalyptic number.

It is an amenable number.

21621566454156 is an abundant number, since it is smaller than the sum of its proper divisors (33290890803684).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21621566454156 is a wasteful number, since it uses less digits than its factorization.

21621566454156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 827943 (or 827938 counting only the distinct ones).

The product of its digits is 10368000, while the sum is 54.

The spelling of 21621566454156 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred sixty-six million, four hundred fifty-four thousand, one hundred fifty-six".