21152516506 has 24 divisors (see below), whose sum is σ = 34963436340. Its totient is φ = 9590518080.

The previous prime is 21152516501. The next prime is 21152516531. The reversal of 21152516506 is 60561525112.

It can be written as a sum of positive squares in 2 ways, for example, as 20825087481 + 327429025 = 144309^2 + 18095^2 .

It is not an unprimeable number, because it can be changed into a prime (21152516501) 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, 14011 + ... + 206158.

Almost surely, 2^21152516506 is an apocalyptic number.

21152516506 is a deficient number, since it is larger than the sum of its proper divisors (13810919834).

21152516506 is a wasteful number, since it uses less digits than its factorization.

21152516506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220590 (or 220579 counting only the distinct ones).

The product of its (nonzero) digits is 18000, while the sum is 34.

The spelling of 21152516506 in words is "twenty-one billion, one hundred fifty-two million, five hundred sixteen thousand, five hundred six".