638691478018 has 16 divisors (see below), whose sum is σ = 1045151786880. Its totient is φ = 290308675600.

The previous prime is 638691478013. The next prime is 638691478057. The reversal of 638691478018 is 810874196836.

It is not an unprimeable number, because it can be changed into a prime (638691478013) 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 7 ways as a sum of consecutive naturals, for example, 1009623 + ... + 1515493.

It is an arithmetic number, because the mean of its divisors is an integer number (65321986680).

Almost surely, 2^638691478018 is an apocalyptic number.

638691478018 is a deficient number, since it is larger than the sum of its proper divisors (406460308862).

638691478018 is a wasteful number, since it uses less digits than its factorization.

638691478018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563273.

The product of its (nonzero) digits is 13934592, while the sum is 61.

The spelling of 638691478018 in words is "six hundred thirty-eight billion, six hundred ninety-one million, four hundred seventy-eight thousand, eighteen".