66390639 has 12 divisors (see below), whose sum is σ = 102973464. Its totient is φ = 37937424.

The previous prime is 66390629. The next prime is 66390679. The reversal of 66390639 is 93609366.

It is not a de Polignac number, because 66390639 - 2⁸ = 66390383 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66390639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66390629) 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, 225672 + ... + 225965.

It is an arithmetic number, because the mean of its divisors is an integer number (8581122).

Almost surely, 2^66390639 is an apocalyptic number.

66390639 is a deficient number, since it is larger than the sum of its proper divisors (36582825).

66390639 is a wasteful number, since it uses less digits than its factorization.

66390639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 451654 (or 451647 counting only the distinct ones).

The product of its (nonzero) digits is 157464, while the sum is 42.

The square root of 66390639 is about 8148.0451029680. The cubic root of 66390639 is about 404.9197402305.

The spelling of 66390639 in words is "sixty-six million, three hundred ninety thousand, six hundred thirty-nine".