639067969 has 4 divisors (see below), whose sum is σ = 642379396. Its totient is φ = 635756544.

The previous prime is 639067967. The next prime is 639067993. The reversal of 639067969 is 969760936.

It is a happy number.

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 423330625 + 215737344 = 20575^2 + 14688^2 .

It is a cyclic number.

It is not a de Polignac number, because 639067969 - 2¹ = 639067967 is a prime.

It is a super-2 number, since 2×639067969² = 816815738003569922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639067963) 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, 1655424 + ... + 1655809.

It is an arithmetic number, because the mean of its divisors is an integer number (160594849).

Almost surely, 2^639067969 is an apocalyptic number.

It is an amenable number.

639067969 is a deficient number, since it is larger than the sum of its proper divisors (3311427).

639067969 is a wasteful number, since it uses less digits than its factorization.

639067969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3311426.

The product of its (nonzero) digits is 3306744, while the sum is 55.

The square root of 639067969 is about 25279.7936898227. The cubic root of 639067969 is about 861.3553394592.

The spelling of 639067969 in words is "six hundred thirty-nine million, sixty-seven thousand, nine hundred sixty-nine".