21939678 has 24 divisors (see below), whose sum is σ = 47665800. Its totient is φ = 7293264.

The previous prime is 21939667. The next prime is 21939679. The reversal of 21939678 is 87693912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939679) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6088 + ... + 8996.

It is an arithmetic number, because the mean of its divisors is an integer number (1986075).

Almost surely, 2^21939678 is an apocalyptic number.

21939678 is an abundant number, since it is smaller than the sum of its proper divisors (25726122).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21939678 is a wasteful number, since it uses less digits than its factorization.

21939678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3336 (or 3333 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 21939678 is about 4683.9809991075. The cubic root of 21939678 is about 279.9476007388.

The spelling of 21939678 in words is "twenty-one million, nine hundred thirty-nine thousand, six hundred seventy-eight".