21031525 has 12 divisors (see below), whose sum is σ = 26979300. Its totient is φ = 16244480.

The previous prime is 21031487. The next prime is 21031529. The reversal of 21031525 is 52513012.

It can be written as a sum of positive squares in 6 ways, for example, as 2377764 + 18653761 = 1542^2 + 4319^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21031525 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13780 + ... + 15229.

It is an arithmetic number, because the mean of its divisors is an integer number (2248275).

Almost surely, 2^21031525 is an apocalyptic number.

21031525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21031525 is a deficient number, since it is larger than the sum of its proper divisors (5947775).

21031525 is a wasteful number, since it uses less digits than its factorization.

21031525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29048 (or 29043 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21031525 is about 4586.0140645227. The cubic root of 21031525 is about 276.0304043030.

Adding to 21031525 its reverse (52513012), we get a palindrome (73544537).

The spelling of 21031525 in words is "twenty-one million, thirty-one thousand, five hundred twenty-five".