21531345015 has 24 divisors (see below), whose sum is σ = 36358756848. Its totient is φ = 10878992640.

The previous prime is 21531345007. The next prime is 21531345047. The reversal of 21531345015 is 51054313512.

It is not a de Polignac number, because 21531345015 - 2³ = 21531345007 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1982706 + ... + 1993535.

It is an arithmetic number, because the mean of its divisors is an integer number (1514948202).

Almost surely, 2^21531345015 is an apocalyptic number.

21531345015 is a deficient number, since it is larger than the sum of its proper divisors (14827411833).

21531345015 is a wasteful number, since it uses less digits than its factorization.

21531345015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3976287 (or 3976268 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 30.

Adding to 21531345015 its reverse (51054313512), we get a palindrome (72585658527).

The spelling of 21531345015 in words is "twenty-one billion, five hundred thirty-one million, three hundred forty-five thousand, fifteen".