21513521516 has 6 divisors (see below), whose sum is σ = 37648662660. Its totient is φ = 10756760756.

The previous prime is 21513521507. The next prime is 21513521527. The reversal of 21513521516 is 61512531512.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2689190186 + ... + 2689190193.

It is an arithmetic number, because the mean of its divisors is an integer number (6274777110).

Almost surely, 2^21513521516 is an apocalyptic number.

It is an amenable number.

21513521516 is a deficient number, since it is larger than the sum of its proper divisors (16135141144).

21513521516 is a wasteful number, since it uses less digits than its factorization.

21513521516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5378380383 (or 5378380381 counting only the distinct ones).

The product of its digits is 9000, while the sum is 32.

The spelling of 21513521516 in words is "twenty-one billion, five hundred thirteen million, five hundred twenty-one thousand, five hundred sixteen".