642661617 has 16 divisors (see below), whose sum is σ = 944259008. Its totient is φ = 386285760.

The previous prime is 642661609. The next prime is 642661633. The reversal of 642661617 is 716166246.

It is not a de Polignac number, because 642661617 - 2³ = 642661609 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642661637) 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, 189934 + ... + 193287.

It is an arithmetic number, because the mean of its divisors is an integer number (59016188).

Almost surely, 2^642661617 is an apocalyptic number.

It is an amenable number.

642661617 is a deficient number, since it is larger than the sum of its proper divisors (301597391).

642661617 is a wasteful number, since it uses less digits than its factorization.

642661617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 383280.

The product of its digits is 72576, while the sum is 39.

The square root of 642661617 is about 25350.7715267208. The cubic root of 642661617 is about 862.9668654118.

The spelling of 642661617 in words is "six hundred forty-two million, six hundred sixty-one thousand, six hundred seventeen".