21075925 has 12 divisors (see below), whose sum is σ = 28144900. Its totient is φ = 15563520.

The previous prime is 21075919. The next prime is 21075931. The reversal of 21075925 is 52957012.

It is an interprime number because it is at equal distance from previous prime (21075919) and next prime (21075931).

It can be written as a sum of positive squares in 6 ways, for example, as 2748964 + 18326961 = 1658^2 + 4281^2 .

It is not a de Polignac number, because 21075925 - 2³ = 21075917 is a prime.

It is a super-2 number, since 2×21075925² = 888389229211250, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32100 + ... + 32749.

Almost surely, 2^21075925 is an apocalyptic number.

21075925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21075925 is a deficient number, since it is larger than the sum of its proper divisors (7068975).

21075925 is a wasteful number, since it uses less digits than its factorization.

21075925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64872 (or 64867 counting only the distinct ones).

The product of its (nonzero) digits is 6300, while the sum is 31.

The square root of 21075925 is about 4590.8523173807. The cubic root of 21075925 is about 276.2245118885.

The spelling of 21075925 in words is "twenty-one million, seventy-five thousand, nine hundred twenty-five".