21154663521 has 12 divisors (see below), whose sum is σ = 31074647760. Its totient is φ = 13864072920.

The previous prime is 21154663493. The next prime is 21154663573. The reversal of 21154663521 is 12536645112.

21154663521 is a `hidden beast` number, since 2 + 1 + 1 + 546 + 63 + 52 + 1 = 666.

It is not a de Polignac number, because 21154663521 - 2⁵ = 21154663489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21154663021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19919115 + ... + 19920176.

It is an arithmetic number, because the mean of its divisors is an integer number (2589553980).

Almost surely, 2^21154663521 is an apocalyptic number.

It is an amenable number.

21154663521 is a deficient number, since it is larger than the sum of its proper divisors (9919984239).

21154663521 is a wasteful number, since it uses less digits than its factorization.

21154663521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39839356 (or 39839353 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The spelling of 21154663521 in words is "twenty-one billion, one hundred fifty-four million, six hundred sixty-three thousand, five hundred twenty-one".