642338861 has 4 divisors (see below), whose sum is σ = 644838492. Its totient is φ = 639839232.

The previous prime is 642338857. The next prime is 642338881. The reversal of 642338861 is 168833246.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 411481225 + 230857636 = 20285^2 + 15194^2 .

It is a cyclic number.

It is not a de Polignac number, because 642338861 - 2² = 642338857 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 (642338821) 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, 1249430 + ... + 1249943.

It is an arithmetic number, because the mean of its divisors is an integer number (161209623).

Almost surely, 2^642338861 is an apocalyptic number.

It is an amenable number.

642338861 is a deficient number, since it is larger than the sum of its proper divisors (2499631).

642338861 is a wasteful number, since it uses less digits than its factorization.

642338861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2499630.

The product of its digits is 165888, while the sum is 41.

The square root of 642338861 is about 25344.4049249534. The cubic root of 642338861 is about 862.8223754934.

The spelling of 642338861 in words is "six hundred forty-two million, three hundred thirty-eight thousand, eight hundred sixty-one".