21608975 has 6 divisors (see below), whose sum is σ = 26795160. Its totient is φ = 17287160.

The previous prime is 21608969. The next prime is 21608987. The reversal of 21608975 is 57980612.

It is not a de Polignac number, because 21608975 - 2⁴ = 21608959 is a prime.

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 5 ways as a sum of consecutive naturals, for example, 432155 + ... + 432204.

It is an arithmetic number, because the mean of its divisors is an integer number (4465860).

Almost surely, 2^21608975 is an apocalyptic number.

21608975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21608975 is a deficient number, since it is larger than the sum of its proper divisors (5186185).

21608975 is an equidigital number, since it uses as much as digits as its factorization.

21608975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 864369 (or 864364 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21608975 is about 4648.5454714351. The cubic root of 21608975 is about 278.5338971384.

The spelling of 21608975 in words is "twenty-one million, six hundred eight thousand, nine hundred seventy-five".