20664139 has 2 divisors, whose sum is σ = 20664140. Its totient is φ = 20664138.

The previous prime is 20664131. The next prime is 20664239. The reversal of 20664139 is 93146602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20664139 - 2³ = 20664131 is a prime.

It is a super-2 number, since 2×20664139² = 854013281222642, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20664139.

It is not a weakly prime, because it can be changed into another prime (20664131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332069 + 10332070.

It is an arithmetic number, because the mean of its divisors is an integer number (10332070).

Almost surely, 2^20664139 is an apocalyptic number.

20664139 is a deficient number, since it is larger than the sum of its proper divisors (1).

20664139 is an equidigital number, since it uses as much as digits as its factorization.

20664139 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 20664139 is about 4545.7825508926. The cubic root of 20664139 is about 274.4136885892.

The spelling of 20664139 in words is "twenty million, six hundred sixty-four thousand, one hundred thirty-nine".