21051525 has 96 divisors (see below), whose sum is σ = 42854400. Its totient is φ = 8985600.

The previous prime is 21051523. The next prime is 21051529. The reversal of 21051525 is 52515012.

It is not a de Polignac number, because 21051525 - 2¹ = 21051523 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051523) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 266436 + ... + 266514.

It is an arithmetic number, because the mean of its divisors is an integer number (446400).

Almost surely, 2^21051525 is an apocalyptic number.

21051525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21051525 is an abundant number, since it is smaller than the sum of its proper divisors (21802875).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21051525 is a wasteful number, since it uses less digits than its factorization.

21051525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 21051525 is about 4588.1940891815. The cubic root of 21051525 is about 276.1178739319.

Adding to 21051525 its reverse (52515012), we get a palindrome (73566537).

The spelling of 21051525 in words is "twenty-one million, fifty-one thousand, five hundred twenty-five".