646633691 has 16 divisors (see below), whose sum is σ = 716601600. Its totient is φ = 578601120.

The previous prime is 646633679. The next prime is 646633693. The reversal of 646633691 is 196336646.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646633691 is a prime.

It is not an unprimeable number, because it can be changed into a prime (646633693) 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, 194360 + ... + 197658.

It is an arithmetic number, because the mean of its divisors is an integer number (44787600).

Almost surely, 2^646633691 is an apocalyptic number.

646633691 is a deficient number, since it is larger than the sum of its proper divisors (69967909).

646633691 is a wasteful number, since it uses less digits than its factorization.

646633691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3586.

The product of its digits is 419904, while the sum is 44.

The square root of 646633691 is about 25428.9931180926. The cubic root of 646633691 is about 864.7411171326.

The spelling of 646633691 in words is "six hundred forty-six million, six hundred thirty-three thousand, six hundred ninety-one".