21054601521 has 12 divisors (see below), whose sum is σ = 30707467648. Its totient is φ = 13900124664.

The previous prime is 21054601517. The next prime is 21054601523. The reversal of 21054601521 is 12510645012.

21054601521 is a `hidden beast` number, since 2 + 1 + 0 + 5 + 4 + 601 + 52 + 1 = 666.

It is not a de Polignac number, because 21054601521 - 2² = 21054601517 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21054601523) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11355385 + ... + 11357238.

Almost surely, 2^21054601521 is an apocalyptic number.

It is an amenable number.

21054601521 is a deficient number, since it is larger than the sum of its proper divisors (9652866127).

21054601521 is a wasteful number, since it uses less digits than its factorization.

21054601521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22712732 (or 22712729 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

The spelling of 21054601521 in words is "twenty-one billion, fifty-four million, six hundred one thousand, five hundred twenty-one".