21138964 has 24 divisors (see below), whose sum is σ = 46122048. Its totient is φ = 8235840.

The previous prime is 21138959. The next prime is 21138977. The reversal of 21138964 is 46983112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34009 + ... + 34624.

It is an arithmetic number, because the mean of its divisors is an integer number (1921752).

Almost surely, 2^21138964 is an apocalyptic number.

It is an amenable number.

21138964 is an abundant number, since it is smaller than the sum of its proper divisors (24983084).

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

21138964 is a wasteful number, since it uses less digits than its factorization.

21138964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68655 (or 68653 counting only the distinct ones).

The product of its digits is 10368, while the sum is 34.

The square root of 21138964 is about 4597.7129096976. The cubic root of 21138964 is about 276.4996375729.

The spelling of 21138964 in words is "twenty-one million, one hundred thirty-eight thousand, nine hundred sixty-four".