642138678 has 24 divisors (see below), whose sum is σ = 1442831208. Its totient is φ = 214046064.

The previous prime is 642138667. The next prime is 642138683. The reversal of 642138678 is 876831246.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 660151 + ... + 661122.

It is an arithmetic number, because the mean of its divisors is an integer number (60117967).

Almost surely, 2^642138678 is an apocalyptic number.

642138678 is an abundant number, since it is smaller than the sum of its proper divisors (800692530).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

642138678 is a wasteful number, since it uses less digits than its factorization.

642138678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1321290 (or 1321278 counting only the distinct ones).

The product of its digits is 387072, while the sum is 45.

The square root of 642138678 is about 25340.4553629172. The cubic root of 642138678 is about 862.7327341696.

The spelling of 642138678 in words is "six hundred forty-two million, one hundred thirty-eight thousand, six hundred seventy-eight".