21608939 has 8 divisors (see below), whose sum is σ = 23651568. Its totient is φ = 19579360.

The previous prime is 21608929. The next prime is 21608941. The reversal of 21608939 is 93980612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21608939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21608929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 389 + ... + 6585.

It is an arithmetic number, because the mean of its divisors is an integer number (2956446).

Almost surely, 2^21608939 is an apocalyptic number.

21608939 is a deficient number, since it is larger than the sum of its proper divisors (2042629).

21608939 is a wasteful number, since it uses less digits than its factorization.

21608939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6525.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21608939 is about 4648.5415992545. The cubic root of 21608939 is about 278.5337424615.

The spelling of 21608939 in words is "twenty-one million, six hundred eight thousand, nine hundred thirty-nine".