21531503525 has 12 divisors (see below), whose sum is σ = 30513216672. Its totient is φ = 14764459440.

The previous prime is 21531503507. The next prime is 21531503537. The reversal of 21531503525 is 52530513512.

It is a de Polignac number, because none of the positive numbers 2^k-21531503525 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21531503491 and 21531503500.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 61518407 + ... + 61518756.

It is an arithmetic number, because the mean of its divisors is an integer number (2542768056).

Almost surely, 2^21531503525 is an apocalyptic number.

21531503525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21531503525 is a deficient number, since it is larger than the sum of its proper divisors (8981713147).

21531503525 is a wasteful number, since it uses less digits than its factorization.

21531503525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123037180 (or 123037175 counting only the distinct ones).

The product of its (nonzero) digits is 22500, while the sum is 32.

The spelling of 21531503525 in words is "twenty-one billion, five hundred thirty-one million, five hundred three thousand, five hundred twenty-five".