642666939 has 16 divisors (see below), whose sum is σ = 866578944. Its totient is φ = 423612000.

The previous prime is 642666919. The next prime is 642666967. The reversal of 642666939 is 939666246.

It is not a de Polignac number, because 642666939 - 2⁸ = 642666683 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 642666891 and 642666900.

It is not an unprimeable number, because it can be changed into a prime (642666919) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 372132 + ... + 373854.

It is an arithmetic number, because the mean of its divisors is an integer number (54161184).

Almost surely, 2^642666939 is an apocalyptic number.

642666939 is a deficient number, since it is larger than the sum of its proper divisors (223912005).

642666939 is a wasteful number, since it uses less digits than its factorization.

642666939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3058.

The product of its digits is 2519424, while the sum is 51.

The square root of 642666939 is about 25350.8764937231. The cubic root of 642666939 is about 862.9692475347.

The spelling of 642666939 in words is "six hundred forty-two million, six hundred sixty-six thousand, nine hundred thirty-nine".