21750645 has 32 divisors (see below), whose sum is σ = 40458240. Its totient is φ = 9771840.

The previous prime is 21750629. The next prime is 21750661. The reversal of 21750645 is 54605712.

It is an interprime number because it is at equal distance from previous prime (21750629) and next prime (21750661).

It is not a de Polignac number, because 21750645 - 2⁴ = 21750629 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, 4440 + ... + 7950.

It is an arithmetic number, because the mean of its divisors is an integer number (1264320).

Almost surely, 2^21750645 is an apocalyptic number.

It is an amenable number.

21750645 is a deficient number, since it is larger than the sum of its proper divisors (18707595).

21750645 is a wasteful number, since it uses less digits than its factorization.

21750645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3585.

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 21750645 is about 4663.7586772902. The cubic root of 21750645 is about 279.1412678558.

The spelling of 21750645 in words is "twenty-one million, seven hundred fifty thousand, six hundred forty-five".