21760639 has 2 divisors, whose sum is σ = 21760640. Its totient is φ = 21760638.

The previous prime is 21760633. The next prime is 21760679. The reversal of 21760639 is 93606712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21760639 - 2⁷ = 21760511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21760633) 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 as a sum of consecutive naturals, namely, 10880319 + 10880320.

It is an arithmetic number, because the mean of its divisors is an integer number (10880320).

Almost surely, 2^21760639 is an apocalyptic number.

21760639 is a deficient number, since it is larger than the sum of its proper divisors (1).

21760639 is an equidigital number, since it uses as much as digits as its factorization.

21760639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13608, while the sum is 34.

The square root of 21760639 is about 4664.8300076209. The cubic root of 21760639 is about 279.1840146443.

The spelling of 21760639 in words is "twenty-one million, seven hundred sixty thousand, six hundred thirty-nine".