646979811 has 32 divisors (see below), whose sum is σ = 952803840. Its totient is φ = 388675584.

The previous prime is 646979803. The next prime is 646979813. The reversal of 646979811 is 118979646.

It is a happy number.

It is not a de Polignac number, because 646979811 - 2³ = 646979803 is a prime.

It is not an unprimeable number, because it can be changed into a prime (646979813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 251745 + ... + 254301.

It is an arithmetic number, because the mean of its divisors is an integer number (29775120).

Almost surely, 2^646979811 is an apocalyptic number.

646979811 is a deficient number, since it is larger than the sum of its proper divisors (305824029).

646979811 is a wasteful number, since it uses less digits than its factorization.

646979811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2795.

The product of its digits is 653184, while the sum is 51.

The square root of 646979811 is about 25435.7978251125. The cubic root of 646979811 is about 864.8953779932.

The spelling of 646979811 in words is "six hundred forty-six million, nine hundred seventy-nine thousand, eight hundred eleven".