646641947 has 16 divisors (see below), whose sum is σ = 756595200. Its totient is φ = 541209600.

The previous prime is 646641901. The next prime is 646641959. The reversal of 646641947 is 749146646.

It is a cyclic number.

It is not a de Polignac number, because 646641947 - 2⁶ = 646641883 is a prime.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646641647) 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, 57179 + ... + 67547.

It is an arithmetic number, because the mean of its divisors is an integer number (47287200).

Almost surely, 2^646641947 is an apocalyptic number.

646641947 is a deficient number, since it is larger than the sum of its proper divisors (109953253).

646641947 is a wasteful number, since it uses less digits than its factorization.

646641947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10586.

The product of its digits is 870912, while the sum is 47.

The square root of 646641947 is about 25429.1554519610. The cubic root of 646641947 is about 864.7447973575.

The spelling of 646641947 in words is "six hundred forty-six million, six hundred forty-one thousand, nine hundred forty-seven".