21639613 has 8 divisors (see below), whose sum is σ = 22982400. Its totient is φ = 20317248.

The previous prime is 21639587. The next prime is 21639647. The reversal of 21639613 is 31693612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21639613 - 2²¹ = 19542461 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21639313) 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 7 ways as a sum of consecutive naturals, for example, 2893 + ... + 7186.

It is an arithmetic number, because the mean of its divisors is an integer number (2872800).

Almost surely, 2^21639613 is an apocalyptic number.

It is an amenable number.

21639613 is a deficient number, since it is larger than the sum of its proper divisors (1342787).

21639613 is a wasteful number, since it uses less digits than its factorization.

21639613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10211.

The product of its digits is 5832, while the sum is 31.

The square root of 21639613 is about 4651.8397435853. The cubic root of 21639613 is about 278.6654735099.

The spelling of 21639613 in words is "twenty-one million, six hundred thirty-nine thousand, six hundred thirteen".