639834729 has 16 divisors (see below), whose sum is σ = 906442560. Its totient is φ = 401455680.

The previous prime is 639834719. The next prime is 639834737. The reversal of 639834729 is 927438936.

It is not a de Polignac number, because 639834729 - 2²¹ = 637737577 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (639834719) 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 15 ways as a sum of consecutive naturals, for example, 6967 + ... + 36444.

It is an arithmetic number, because the mean of its divisors is an integer number (56652660).

Almost surely, 2^639834729 is an apocalyptic number.

It is an amenable number.

639834729 is a deficient number, since it is larger than the sum of its proper divisors (266607831).

639834729 is an equidigital number, since it uses as much as digits as its factorization.

639834729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43465 (or 43431 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 51.

The square root of 639834729 is about 25294.9546154960. The cubic root of 639834729 is about 861.6996892982.

The spelling of 639834729 in words is "six hundred thirty-nine million, eight hundred thirty-four thousand, seven hundred twenty-nine".