639117869 has 4 divisors (see below), whose sum is σ = 688280796. Its totient is φ = 589954944.

The previous prime is 639117833. The next prime is 639117887. The reversal of 639117869 is 968711936.

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

It can be written as a sum of positive squares in 2 ways, for example, as 130074025 + 509043844 = 11405^2 + 22562^2 .

It is a cyclic number.

It is not a de Polignac number, because 639117869 - 2¹⁶ = 639052333 is a prime.

It is a super-2 number, since 2×639117869² = 816943300950202322, 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 (639117569) 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, 24581444 + ... + 24581469.

It is an arithmetic number, because the mean of its divisors is an integer number (172070199).

Almost surely, 2^639117869 is an apocalyptic number.

It is an amenable number.

639117869 is a deficient number, since it is larger than the sum of its proper divisors (49162927).

639117869 is a wasteful number, since it uses less digits than its factorization.

639117869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49162926.

The product of its digits is 489888, while the sum is 50.

The square root of 639117869 is about 25280.7806248146. The cubic root of 639117869 is about 861.3777577907.

The spelling of 639117869 in words is "six hundred thirty-nine million, one hundred seventeen thousand, eight hundred sixty-nine".