21011525 has 12 divisors (see below), whose sum is σ = 26120352. Its totient is φ = 16766640.

The previous prime is 21011519. The next prime is 21011531. The reversal of 21011525 is 52511012.

It is an interprime number because it is at equal distance from previous prime (21011519) and next prime (21011531).

It is not a de Polignac number, because 21011525 - 2⁴ = 21011509 is a prime.

It is a Duffinian number.

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, 12272 + ... + 13878.

It is an arithmetic number, because the mean of its divisors is an integer number (2176696).

Almost surely, 2^21011525 is an apocalyptic number.

21011525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21011525 is a deficient number, since it is larger than the sum of its proper divisors (5108827).

21011525 is a wasteful number, since it uses less digits than its factorization.

21011525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2140 (or 2135 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 21011525 is about 4583.8330030663. The cubic root of 21011525 is about 275.9428792034.

Adding to 21011525 its reverse (52511012), we get a palindrome (73522537).

The spelling of 21011525 in words is "twenty-one million, eleven thousand, five hundred twenty-five".