646691377 has 6 divisors (see below), whose sum is σ = 660745778. Its totient is φ = 632929824.

The previous prime is 646691369. The next prime is 646691453. The reversal of 646691377 is 773196646.

It is a happy number.

646691377 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 581340321 + 65351056 = 24111^2 + 8084^2 .

It is not a de Polignac number, because 646691377 - 2³ = 646691369 is a prime.

It is a super-2 number, since 2×646691377² = 836419474172312258, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 646691377.

It is not an unprimeable number, because it can be changed into a prime (646691477) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 144168 + ... + 148585.

Almost surely, 2^646691377 is an apocalyptic number.

It is an amenable number.

646691377 is a deficient number, since it is larger than the sum of its proper divisors (14054401).

646691377 is an equidigital number, since it uses as much as digits as its factorization.

646691377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292847 (or 292800 counting only the distinct ones).

The product of its digits is 1143072, while the sum is 49.

The square root of 646691377 is about 25430.1273492682. The cubic root of 646691377 is about 864.7668308009.

The spelling of 646691377 in words is "six hundred forty-six million, six hundred ninety-one thousand, three hundred seventy-seven".