21708938 has 8 divisors (see below), whose sum is σ = 33049632. Its totient is φ = 10692396.

The previous prime is 21708931. The next prime is 21708943. The reversal of 21708938 is 83980712.

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

It is not an unprimeable number, because it can be changed into a prime (21708931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80870 + ... + 81137.

It is an arithmetic number, because the mean of its divisors is an integer number (4131204).

Almost surely, 2^21708938 is an apocalyptic number.

21708938 is a deficient number, since it is larger than the sum of its proper divisors (11340694).

21708938 is a wasteful number, since it uses less digits than its factorization.

21708938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162076.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 21708938 is about 4659.2851383018. The cubic root of 21708938 is about 278.9627353098.

The spelling of 21708938 in words is "twenty-one million, seven hundred eight thousand, nine hundred thirty-eight".