642909178 has 12 divisors (see below), whose sum is σ = 998766990. Its totient is φ = 310369136.

The previous prime is 642909167. The next prime is 642909187. The reversal of 642909178 is 871909246.

It can be written as a sum of positive squares in 3 ways, for example, as 418898089 + 224011089 = 20467^2 + 14967^2 .

It is a super-2 number, since 2×642909178² = 826664422313271368, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 189433 + ... + 192796.

Almost surely, 2^642909178 is an apocalyptic number.

642909178 is a deficient number, since it is larger than the sum of its proper divisors (355857812).

642909178 is a wasteful number, since it uses less digits than its factorization.

642909178 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382289 (or 382260 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 642909178 is about 25355.6537679469. The cubic root of 642909178 is about 863.0776595988.

The spelling of 642909178 in words is "six hundred forty-two million, nine hundred nine thousand, one hundred seventy-eight".