638193751381 has 4 divisors (see below), whose sum is σ = 644158179072. Its totient is φ = 632229323692.

The previous prime is 638193751309. The next prime is 638193751411. The reversal of 638193751381 is 183157391836.

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 638193751381 - 2³⁹ = 88437937493 is a prime.

It is a super-2 number, since 2×638193751381² (a number of 24 digits) contains 22 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 (638193751681) 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, 2982213685 + ... + 2982213898.

It is an arithmetic number, because the mean of its divisors is an integer number (161039544768).

Almost surely, 2^638193751381 is an apocalyptic number.

It is an amenable number.

638193751381 is a deficient number, since it is larger than the sum of its proper divisors (5964427691).

638193751381 is a wasteful number, since it uses less digits than its factorization.

638193751381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5964427690.

The product of its digits is 3265920, while the sum is 55.

The spelling of 638193751381 in words is "six hundred thirty-eight billion, one hundred ninety-three million, seven hundred fifty-one thousand, three hundred eighty-one".