639731973497 has 4 divisors (see below), whose sum is σ = 641014002000. Its totient is φ = 638449944996.

The previous prime is 639731973493. The next prime is 639731973521. The reversal of 639731973497 is 794379137936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 639731973497 - 2² = 639731973493 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639731973493) 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, 641013503 + ... + 641014500.

It is an arithmetic number, because the mean of its divisors is an integer number (160253500500).

Almost surely, 2^639731973497 is an apocalyptic number.

It is an amenable number.

639731973497 is a deficient number, since it is larger than the sum of its proper divisors (1282028503).

639731973497 is a wasteful number, since it uses less digits than its factorization.

639731973497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1282028502.

The product of its digits is 162030456, while the sum is 68.

The spelling of 639731973497 in words is "six hundred thirty-nine billion, seven hundred thirty-one million, nine hundred seventy-three thousand, four hundred ninety-seven".