639491403 has 4 divisors (see below), whose sum is σ = 852655208. Its totient is φ = 426327600.

The previous prime is 639491351. The next prime is 639491443. The reversal of 639491403 is 304194936.

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

It is not a de Polignac number, because 639491403 - 2⁶ = 639491339 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639491443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106581898 + ... + 106581903.

It is an arithmetic number, because the mean of its divisors is an integer number (213163802).

Almost surely, 2^639491403 is an apocalyptic number.

639491403 is a deficient number, since it is larger than the sum of its proper divisors (213163805).

639491403 is a wasteful number, since it uses less digits than its factorization.

639491403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213163804.

The product of its (nonzero) digits is 69984, while the sum is 39.

The square root of 639491403 is about 25288.1672526895. The cubic root of 639491403 is about 861.5455365537.

The spelling of 639491403 in words is "six hundred thirty-nine million, four hundred ninety-one thousand, four hundred three".