66390647 has 4 divisors (see below), whose sum is σ = 66913536. Its totient is φ = 65867760.

The previous prime is 66390629. The next prime is 66390679. The reversal of 66390647 is 74609366.

It is a happy number.

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 66390647 - 2⁸ = 66390391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66390347) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261254 + ... + 261507.

It is an arithmetic number, because the mean of its divisors is an integer number (16728384).

Almost surely, 2^66390647 is an apocalyptic number.

66390647 is a deficient number, since it is larger than the sum of its proper divisors (522889).

66390647 is a wasteful number, since it uses less digits than its factorization.

66390647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 522888.

The product of its (nonzero) digits is 163296, while the sum is 41.

The square root of 66390647 is about 8148.0455938832. The cubic root of 66390647 is about 404.9197564947.

The spelling of 66390647 in words is "sixty-six million, three hundred ninety thousand, six hundred forty-seven".