639721473 has 8 divisors (see below), whose sum is σ = 853079328. Its totient is φ = 426422304.

The previous prime is 639721447. The next prime is 639721529. The reversal of 639721473 is 374127936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 639721473 - 2¹⁰ = 639720449 is a prime.

It is not an unprimeable number, because it can be changed into a prime (639721403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31765 + ... + 47837.

It is an arithmetic number, because the mean of its divisors is an integer number (106634916).

Almost surely, 2^639721473 is an apocalyptic number.

It is an amenable number.

639721473 is a deficient number, since it is larger than the sum of its proper divisors (213357855).

639721473 is a wasteful number, since it uses less digits than its factorization.

639721473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29343.

The product of its digits is 190512, while the sum is 42.

The square root of 639721473 is about 25292.7158091020. The cubic root of 639721473 is about 861.6488436583.

The spelling of 639721473 in words is "six hundred thirty-nine million, seven hundred twenty-one thousand, four hundred seventy-three".