639447939 has 48 divisors (see below), whose sum is σ = 1046433024. Its totient is φ = 387828000.

The previous prime is 639447937. The next prime is 639447947. The reversal of 639447939 is 939744936.

It is not a de Polignac number, because 639447939 - 2¹ = 639447937 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639447937) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 222864 + ... + 225714.

It is an arithmetic number, because the mean of its divisors is an integer number (21800688).

Almost surely, 2^639447939 is an apocalyptic number.

639447939 is a deficient number, since it is larger than the sum of its proper divisors (406985085).

639447939 is a wasteful number, since it uses less digits than its factorization.

639447939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2950 (or 2938 counting only the distinct ones).

The product of its digits is 4408992, while the sum is 54.

The square root of 639447939 is about 25287.3078638277. The cubic root of 639447939 is about 861.5260173632.

The spelling of 639447939 in words is "six hundred thirty-nine million, four hundred forty-seven thousand, nine hundred thirty-nine".