642660639 has 8 divisors (see below), whose sum is σ = 907285680. Its totient is φ = 403238016.

The previous prime is 642660631. The next prime is 642660647. The reversal of 642660639 is 936066246.

It is an interprime number because it is at equal distance from previous prime (642660631) and next prime (642660647).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 642660639 - 2³ = 642660631 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 642660639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642660631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6300544 + ... + 6300645.

It is an arithmetic number, because the mean of its divisors is an integer number (113410710).

Almost surely, 2^642660639 is an apocalyptic number.

642660639 is a deficient number, since it is larger than the sum of its proper divisors (264625041).

642660639 is a wasteful number, since it uses less digits than its factorization.

642660639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12601209.

The product of its (nonzero) digits is 279936, while the sum is 42.

The square root of 642660639 is about 25350.7522373597. The cubic root of 642660639 is about 862.9664276583.

The spelling of 642660639 in words is "six hundred forty-two million, six hundred sixty thousand, six hundred thirty-nine".