638376561385 has 4 divisors (see below), whose sum is σ = 766051873668. Its totient is φ = 510701249104.

The previous prime is 638376561373. The next prime is 638376561439. The reversal of 638376561385 is 583165673836.

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

It can be written as a sum of positive squares in 2 ways, for example, as 157384378089 + 480992183296 = 396717^2 + 693536^2 .

It is a cyclic number.

It is not a de Polignac number, because 638376561385 - 2⁹ = 638376560873 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63837656134 + ... + 63837656143.

It is an arithmetic number, because the mean of its divisors is an integer number (191512968417).

Almost surely, 2^638376561385 is an apocalyptic number.

It is an amenable number.

638376561385 is a deficient number, since it is larger than the sum of its proper divisors (127675312283).

638376561385 is a wasteful number, since it uses less digits than its factorization.

638376561385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127675312282.

The product of its digits is 65318400, while the sum is 61.

The spelling of 638376561385 in words is "six hundred thirty-eight billion, three hundred seventy-six million, five hundred sixty-one thousand, three hundred eighty-five".