638372686609 has 4 divisors (see below), whose sum is σ = 729568784704. Its totient is φ = 547176588516.

The previous prime is 638372686559. The next prime is 638372686657. The reversal of 638372686609 is 906686273836.

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 638372686609 - 2¹⁷ = 638372555537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638372606609) 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, 45598049037 + ... + 45598049050.

It is an arithmetic number, because the mean of its divisors is an integer number (182392196176).

Almost surely, 2^638372686609 is an apocalyptic number.

It is an amenable number.

638372686609 is a deficient number, since it is larger than the sum of its proper divisors (91196098095).

638372686609 is an equidigital number, since it uses as much as digits as its factorization.

638372686609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91196098094.

The product of its (nonzero) digits is 94058496, while the sum is 64.

The spelling of 638372686609 in words is "six hundred thirty-eight billion, three hundred seventy-two million, six hundred eighty-six thousand, six hundred nine".