668236639 has 16 divisors (see below), whose sum is σ = 780950016. Its totient is φ = 559951200.

The previous prime is 668236637. The next prime is 668236643. The reversal of 668236639 is 936632866.

It is a cyclic number.

It is not a de Polignac number, because 668236639 - 2¹ = 668236637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 668236592 and 668236601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668236637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66624 + ... + 75994.

It is an arithmetic number, because the mean of its divisors is an integer number (48809376).

Almost surely, 2^668236639 is an apocalyptic number.

668236639 is a deficient number, since it is larger than the sum of its proper divisors (112713377).

668236639 is a wasteful number, since it uses less digits than its factorization.

668236639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9606.

The product of its digits is 1679616, while the sum is 49.

The square root of 668236639 is about 25850.2734801781. The cubic root of 668236639 is about 874.2656757166.

The spelling of 668236639 in words is "six hundred sixty-eight million, two hundred thirty-six thousand, six hundred thirty-nine".