639722669 has 4 divisors (see below), whose sum is σ = 640355196. Its totient is φ = 639090144.

The previous prime is 639722659. The next prime is 639722689. The reversal of 639722669 is 966227936.

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 34070569 + 605652100 = 5837^2 + 24610^2 .

It is a cyclic number.

It is not a de Polignac number, because 639722669 - 2¹⁶ = 639657133 is a prime.

It is a super-2 number, since 2×639722669² = 818490186464967122, 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 (639722639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 314744 + ... + 316769.

It is an arithmetic number, because the mean of its divisors is an integer number (160088799).

Almost surely, 2^639722669 is an apocalyptic number.

It is an amenable number.

639722669 is a deficient number, since it is larger than the sum of its proper divisors (632527).

639722669 is a wasteful number, since it uses less digits than its factorization.

639722669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 632526.

The product of its digits is 1469664, while the sum is 50.

The square root of 639722669 is about 25292.7394522618. The cubic root of 639722669 is about 861.6493806270.

The spelling of 639722669 in words is "six hundred thirty-nine million, seven hundred twenty-two thousand, six hundred sixty-nine".