646935681 has 12 divisors (see below), whose sum is σ = 1003410672. Its totient is φ = 369677448.

The previous prime is 646935677. The next prime is 646935689. The reversal of 646935681 is 186539646.

It is not a de Polignac number, because 646935681 - 2² = 646935677 is a prime.

It is a super-2 number, since 2×646935681² = 837051550701867522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 646935681.

It is not an unprimeable number, because it can be changed into a prime (646935689) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2200315 + ... + 2200608.

It is an arithmetic number, because the mean of its divisors is an integer number (83617556).

Almost surely, 2^646935681 is an apocalyptic number.

It is an amenable number.

646935681 is a deficient number, since it is larger than the sum of its proper divisors (356474991).

646935681 is a wasteful number, since it uses less digits than its factorization.

646935681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4400940 (or 4400933 counting only the distinct ones).

The product of its digits is 933120, while the sum is 48.

The square root of 646935681 is about 25434.9303321240. The cubic root of 646935681 is about 864.8757129278.

The spelling of 646935681 in words is "six hundred forty-six million, nine hundred thirty-five thousand, six hundred eighty-one".