646636405 has 16 divisors (see below), whose sum is σ = 828316800. Its totient is φ = 483174720.

The previous prime is 646636391. The next prime is 646636427. The reversal of 646636405 is 504636646.

It is not a de Polignac number, because 646636405 - 2⁹ = 646635893 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41190 + ... + 54679.

It is an arithmetic number, because the mean of its divisors is an integer number (51769800).

Almost surely, 2^646636405 is an apocalyptic number.

It is an amenable number.

646636405 is a deficient number, since it is larger than the sum of its proper divisors (181680395).

646636405 is a wasteful number, since it uses less digits than its factorization.

646636405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95964.

The product of its (nonzero) digits is 311040, while the sum is 40.

The square root of 646636405 is about 25429.0464823202. The cubic root of 646636405 is about 864.7423269387.

The spelling of 646636405 in words is "six hundred forty-six million, six hundred thirty-six thousand, four hundred five".