639139471 has 4 divisors (see below), whose sum is σ = 641791744. Its totient is φ = 636487200.

The previous prime is 639139453. The next prime is 639139477. The reversal of 639139471 is 174931936.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639139471 - 2⁹ = 639138959 is a prime.

It is a super-3 number, since 3×639139471³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639139477) 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, 1325775 + ... + 1326256.

It is an arithmetic number, because the mean of its divisors is an integer number (160447936).

Almost surely, 2^639139471 is an apocalyptic number.

639139471 is a deficient number, since it is larger than the sum of its proper divisors (2652273).

639139471 is a wasteful number, since it uses less digits than its factorization.

639139471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2652272.

The product of its digits is 122472, while the sum is 43.

The square root of 639139471 is about 25281.2078627585. The cubic root of 639139471 is about 861.3874624548.

The spelling of 639139471 in words is "six hundred thirty-nine million, one hundred thirty-nine thousand, four hundred seventy-one".