21975641 has 4 divisors (see below), whose sum is σ = 22202292. Its totient is φ = 21748992.

The previous prime is 21975637. The next prime is 21975691. The reversal of 21975641 is 14657912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14707225 + 7268416 = 3835^2 + 2696^2 .

It is a cyclic number.

It is not a de Polignac number, because 21975641 - 2² = 21975637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21975601) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 113180 + ... + 113373.

It is an arithmetic number, because the mean of its divisors is an integer number (5550573).

Almost surely, 2^21975641 is an apocalyptic number.

It is an amenable number.

21975641 is a deficient number, since it is larger than the sum of its proper divisors (226651).

21975641 is an equidigital number, since it uses as much as digits as its factorization.

21975641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226650.

The product of its digits is 15120, while the sum is 35.

The square root of 21975641 is about 4687.8183625222. The cubic root of 21975641 is about 280.1004783947.

The spelling of 21975641 in words is "twenty-one million, nine hundred seventy-five thousand, six hundred forty-one".