21247375 has 32 divisors (see below), whose sum is σ = 28005120. Its totient is φ = 16077600.

The previous prime is 21247367. The next prime is 21247381. The reversal of 21247375 is 57374212.

It is not a de Polignac number, because 21247375 - 2³ = 21247367 is a prime.

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, 317092 + ... + 317158.

It is an arithmetic number, because the mean of its divisors is an integer number (875160).

Almost surely, 2^21247375 is an apocalyptic number.

21247375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21247375 is a deficient number, since it is larger than the sum of its proper divisors (6757745).

21247375 is an equidigital number, since it uses as much as digits as its factorization.

21247375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184 (or 174 counting only the distinct ones).

The product of its digits is 11760, while the sum is 31.

The square root of 21247375 is about 4609.4874986272. The cubic root of 21247375 is about 276.9715071893.

The spelling of 21247375 in words is "twenty-one million, two hundred forty-seven thousand, three hundred seventy-five".