21535401525 has 72 divisors (see below), whose sum is σ = 41438722752. Its totient is φ = 9827136000.

The previous prime is 21535401521. The next prime is 21535401529. The reversal of 21535401525 is 52510453512.

It is an interprime number because it is at equal distance from previous prime (21535401521) and next prime (21535401529).

It is not a de Polignac number, because 21535401525 - 2² = 21535401521 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21535401521) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 84480 + ... + 224070.

It is an arithmetic number, because the mean of its divisors is an integer number (575537816).

Almost surely, 2^21535401525 is an apocalyptic number.

21535401525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21535401525 is a deficient number, since it is larger than the sum of its proper divisors (19903321227).

21535401525 is a wasteful number, since it uses less digits than its factorization.

21535401525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139643 (or 139627 counting only the distinct ones).

The product of its (nonzero) digits is 30000, while the sum is 33.

The spelling of 21535401525 in words is "twenty-one billion, five hundred thirty-five million, four hundred one thousand, five hundred twenty-five".