21533503051521 has 24 divisors (see below), whose sum is σ = 31591993062240. Its totient is φ = 14131838673216.

The previous prime is 21533503051517. The next prime is 21533503051531. The reversal of 21533503051521 is 12515030533512.

21533503051521 is a `hidden beast` number, since 2 + 1 + 5 + 3 + 3 + 50 + 30 + 51 + 521 = 666.

It is not a de Polignac number, because 21533503051521 - 2² = 21533503051517 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21533503051531) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 59032435 + ... + 59396088.

It is an arithmetic number, because the mean of its divisors is an integer number (1316333044260).

Almost surely, 2^{21533503051521} is an apocalyptic number.

It is an amenable number.

21533503051521 is a deficient number, since it is larger than the sum of its proper divisors (10058490010719).

21533503051521 is a wasteful number, since it uses less digits than its factorization.

21533503051521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118428845 (or 118428842 counting only the distinct ones).

The product of its (nonzero) digits is 67500, while the sum is 36.

The spelling of 21533503051521 in words is "twenty-one trillion, five hundred thirty-three billion, five hundred three million, fifty-one thousand, five hundred twenty-one".