21715375 has 32 divisors (see below), whose sum is σ = 31337280. Its totient is φ = 14848000.

The previous prime is 21715361. The next prime is 21715433. The reversal of 21715375 is 57351712.

It is not a de Polignac number, because 21715375 - 2⁷ = 21715247 is a prime.

It is a super-2 number, since 2×21715375² = 943115022781250, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22911 + ... + 23839.

It is an arithmetic number, because the mean of its divisors is an integer number (979290).

Almost surely, 2^21715375 is an apocalyptic number.

21715375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21715375 is a deficient number, since it is larger than the sum of its proper divisors (9621905).

21715375 is a wasteful number, since it uses less digits than its factorization.

21715375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 972 (or 962 counting only the distinct ones).

The product of its digits is 7350, while the sum is 31.

The square root of 21715375 is about 4659.9758583066. The cubic root of 21715375 is about 278.9903046866.

The spelling of 21715375 in words is "twenty-one million, seven hundred fifteen thousand, three hundred seventy-five".