20664739 has 4 divisors (see below), whose sum is σ = 20678080. Its totient is φ = 20651400.

The previous prime is 20664737. The next prime is 20664781. The reversal of 20664739 is 93746602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20664739 - 2¹ = 20664737 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20664698 and 20664707.

It is not an unprimeable number, because it can be changed into a prime (20664737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3987 + ... + 7564.

It is an arithmetic number, because the mean of its divisors is an integer number (5169520).

Almost surely, 2^20664739 is an apocalyptic number.

20664739 is a deficient number, since it is larger than the sum of its proper divisors (13341).

20664739 is a wasteful number, since it uses less digits than its factorization.

20664739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13340.

The product of its (nonzero) digits is 54432, while the sum is 37.

The square root of 20664739 is about 4545.8485456513. The cubic root of 20664739 is about 274.4163445046.

The spelling of 20664739 in words is "twenty million, six hundred sixty-four thousand, seven hundred thirty-nine".