21906525 has 24 divisors (see below), whose sum is σ = 38127520. Its totient is φ = 11067840.

The previous prime is 21906509. The next prime is 21906541. The reversal of 21906525 is 52560912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21906509) and next prime (21906541).

It is not a de Polignac number, because 21906525 - 2⁴ = 21906509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21906492 and 21906501.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6262 + ... + 9111.

Almost surely, 2^21906525 is an apocalyptic number.

21906525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21906525 is a deficient number, since it is larger than the sum of its proper divisors (16220995).

21906525 is a wasteful number, since it uses less digits than its factorization.

21906525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15405 (or 15400 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 21906525 is about 4680.4406843801. The cubic root of 21906525 is about 279.8065202480.

The spelling of 21906525 in words is "twenty-one million, nine hundred six thousand, five hundred twenty-five".