21213525 has 12 divisors (see below), whose sum is σ = 35073152. Its totient is φ = 11313840.

The previous prime is 21213487. The next prime is 21213553. The reversal of 21213525 is 52531212.

It is not a de Polignac number, because 21213525 - 2⁶ = 21213461 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, 141349 + ... + 141498.

Almost surely, 2^21213525 is an apocalyptic number.

21213525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21213525 is a deficient number, since it is larger than the sum of its proper divisors (13859627).

21213525 is a wasteful number, since it uses less digits than its factorization.

21213525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282860 (or 282855 counting only the distinct ones).

The product of its digits is 600, while the sum is 21.

The square root of 21213525 is about 4605.8142602584. The cubic root of 21213525 is about 276.8243444026.

Adding to 21213525 its reverse (52531212), we get a palindrome (73744737).

The spelling of 21213525 in words is "twenty-one million, two hundred thirteen thousand, five hundred twenty-five".