646385813 has 4 divisors (see below), whose sum is σ = 674489568. Its totient is φ = 618282060.

The previous prime is 646385809. The next prime is 646385863. The reversal of 646385813 is 318583646.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 646385813 - 2² = 646385809 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 (646385863) 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, 14051843 + ... + 14051888.

It is an arithmetic number, because the mean of its divisors is an integer number (168622392).

Almost surely, 2^646385813 is an apocalyptic number.

It is an amenable number.

646385813 is a deficient number, since it is larger than the sum of its proper divisors (28103755).

646385813 is a wasteful number, since it uses less digits than its factorization.

646385813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28103754.

The product of its digits is 414720, while the sum is 44.

The square root of 646385813 is about 25424.1187261230. The cubic root of 646385813 is about 864.6306075314.

The spelling of 646385813 in words is "six hundred forty-six million, three hundred eighty-five thousand, eight hundred thirteen".