21375128525 has 12 divisors (see below), whose sum is σ = 27360165504. Its totient is φ = 16548486000.

The previous prime is 21375128521. The next prime is 21375128531. The reversal of 21375128525 is 52582157312.

It is not a de Polignac number, because 21375128525 - 2² = 21375128521 is a prime.

It is a super-2 number, since 2×21375128525² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375128521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13789631 + ... + 13791180.

It is an arithmetic number, because the mean of its divisors is an integer number (2280013792).

Almost surely, 2^21375128525 is an apocalyptic number.

21375128525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21375128525 is a deficient number, since it is larger than the sum of its proper divisors (5985036979).

21375128525 is a wasteful number, since it uses less digits than its factorization.

21375128525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27580852 (or 27580847 counting only the distinct ones).

The product of its digits is 168000, while the sum is 41.

The spelling of 21375128525 in words is "twenty-one billion, three hundred seventy-five million, one hundred twenty-eight thousand, five hundred twenty-five".