668432639 has 16 divisors (see below), whose sum is σ = 830726208. Its totient is φ = 524662272.

The previous prime is 668432627. The next prime is 668432657. The reversal of 668432639 is 936234866.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668432639 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 668432593 and 668432602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668432659) 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, 71504 + ... + 80309.

It is an arithmetic number, because the mean of its divisors is an integer number (51920388).

Almost surely, 2^668432639 is an apocalyptic number.

668432639 is a deficient number, since it is larger than the sum of its proper divisors (162293569).

668432639 is a wasteful number, since it uses less digits than its factorization.

668432639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151874.

The product of its digits is 1119744, while the sum is 47.

The square root of 668432639 is about 25854.0642646374. The cubic root of 668432639 is about 874.3511441030.

The spelling of 668432639 in words is "six hundred sixty-eight million, four hundred thirty-two thousand, six hundred thirty-nine".