20664138 has 24 divisors (see below), whose sum is σ = 45428544. Its totient is φ = 6261640.

The previous prime is 20664131. The next prime is 20664139. The reversal of 20664138 is 83146602.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (20664131) 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, 13506 + ... + 14957.

It is an arithmetic number, because the mean of its divisors is an integer number (1892856).

Almost surely, 2^20664138 is an apocalyptic number.

20664138 is an abundant number, since it is smaller than the sum of its proper divisors (24764406).

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

20664138 is a wasteful number, since it uses less digits than its factorization.

20664138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28490 (or 28479 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 20664138 is about 4545.7824409006. The cubic root of 20664138 is about 274.4136841626.

It can be divided in two parts, 20664 and 138, that added together give a palindrome (20802).

The spelling of 20664138 in words is "twenty million, six hundred sixty-four thousand, one hundred thirty-eight".