21375637 has 4 divisors (see below), whose sum is σ = 21897036. Its totient is φ = 20854240.

The previous prime is 21375631. The next prime is 21375659. The reversal of 21375637 is 73657312.

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 5447556 + 15928081 = 2334^2 + 3991^2 .

It is not a de Polignac number, because 21375637 - 2¹¹ = 21373589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21375631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260638 + ... + 260719.

It is an arithmetic number, because the mean of its divisors is an integer number (5474259).

Almost surely, 2^21375637 is an apocalyptic number.

It is an amenable number.

21375637 is a deficient number, since it is larger than the sum of its proper divisors (521399).

21375637 is an equidigital number, since it uses as much as digits as its factorization.

21375637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521398.

The product of its digits is 26460, while the sum is 34.

The square root of 21375637 is about 4623.3793917437. The cubic root of 21375637 is about 277.5277119743.

The spelling of 21375637 in words is "twenty-one million, three hundred seventy-five thousand, six hundred thirty-seven".