639762197 has 4 divisors (see below), whose sum is σ = 639932940. Its totient is φ = 639591456.

The previous prime is 639762191. The next prime is 639762203. The reversal of 639762197 is 791267936.

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

It is an interprime number because it is at equal distance from previous prime (639762191) and next prime (639762203).

It can be written as a sum of positive squares in 2 ways, for example, as 227225476 + 412536721 = 15074^2 + 20311^2 .

It is a cyclic number.

It is not a de Polignac number, because 639762197 - 2⁶ = 639762133 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 (639762191) 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, 79622 + ... + 87287.

It is an arithmetic number, because the mean of its divisors is an integer number (159983235).

Almost surely, 2^639762197 is an apocalyptic number.

It is an amenable number.

639762197 is a deficient number, since it is larger than the sum of its proper divisors (170743).

639762197 is a wasteful number, since it uses less digits than its factorization.

639762197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170742.

The product of its digits is 857304, while the sum is 50.

The square root of 639762197 is about 25293.5208502098. The cubic root of 639762197 is about 861.6671271584.

The spelling of 639762197 in words is "six hundred thirty-nine million, seven hundred sixty-two thousand, one hundred ninety-seven".