639969121 has 12 divisors (see below), whose sum is σ = 707347732. Its totient is φ = 578556000.

The previous prime is 639969107. The next prime is 639969137. The reversal of 639969121 is 121969936.

It can be written as a sum of positive squares in 2 ways, for example, as 10962721 + 629006400 = 3311^2 + 25080^2 .

It is not a de Polignac number, because 639969121 - 2¹³ = 639960929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639969151) 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 11 ways as a sum of consecutive naturals, for example, 7291 + ... + 36511.

Almost surely, 2^639969121 is an apocalyptic number.

It is an amenable number.

639969121 is a deficient number, since it is larger than the sum of its proper divisors (67378611).

639969121 is a wasteful number, since it uses less digits than its factorization.

639969121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29424 (or 29413 counting only the distinct ones).

The product of its digits is 157464, while the sum is 46.

The square root of 639969121 is about 25297.6109741612. The cubic root of 639969121 is about 861.7600160422.

The spelling of 639969121 in words is "six hundred thirty-nine million, nine hundred sixty-nine thousand, one hundred twenty-one".