642008191 has 4 divisors (see below), whose sum is σ = 700372584. Its totient is φ = 583643800.

The previous prime is 642008161. The next prime is 642008197. The reversal of 642008191 is 191800246.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 642008191 - 2²³ = 633619583 is a prime.

It is a super-2 number, since 2×642008191² = 824349034622184962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642008197) 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, 29182180 + ... + 29182201.

It is an arithmetic number, because the mean of its divisors is an integer number (175093146).

Almost surely, 2^642008191 is an apocalyptic number.

642008191 is a deficient number, since it is larger than the sum of its proper divisors (58364393).

642008191 is a wasteful number, since it uses less digits than its factorization.

642008191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58364392.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 642008191 is about 25337.8805546162. The cubic root of 642008191 is about 862.6742924672.

The spelling of 642008191 in words is "six hundred forty-two million, eight thousand, one hundred ninety-one".