21133351521 has 16 divisors (see below), whose sum is σ = 32956494400. Its totient is φ = 13347379584.

The previous prime is 21133351517. The next prime is 21133351529. The reversal of 21133351521 is 12515333112.

21133351521 is a `hidden beast` number, since 2 + 1 + 133 + 3 + 5 + 1 + 521 = 666.

It is not a de Polignac number, because 21133351521 - 2² = 21133351517 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21133351529) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20597296 + ... + 20598321.

It is an arithmetic number, because the mean of its divisors is an integer number (2059780900).

Almost surely, 2^21133351521 is an apocalyptic number.

It is an amenable number.

21133351521 is a deficient number, since it is larger than the sum of its proper divisors (11823142879).

21133351521 is a wasteful number, since it uses less digits than its factorization.

21133351521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41195645 (or 41195639 counting only the distinct ones).

The product of its digits is 2700, while the sum is 27.

Adding to 21133351521 its reverse (12515333112), we get a palindrome (33648684633).

The spelling of 21133351521 in words is "twenty-one billion, one hundred thirty-three million, three hundred fifty-one thousand, five hundred twenty-one".