21681675 has 72 divisors (see below), whose sum is σ = 41705664. Its totient is φ = 11158560.

The previous prime is 21681659. The next prime is 21681683. The reversal of 21681675 is 57618612.

It is not a de Polignac number, because 21681675 - 2⁴ = 21681659 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 261184 + ... + 261266.

Almost surely, 2^21681675 is an apocalyptic number.

21681675 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21681675 is a deficient number, since it is larger than the sum of its proper divisors (20023989).

21681675 is an equidigital number, since it uses as much as digits as its factorization.

21681675 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151 (or 134 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21681675 is about 4656.3585557815. The cubic root of 21681675 is about 278.8459086677.

The spelling of 21681675 in words is "twenty-one million, six hundred eighty-one thousand, six hundred seventy-five".