638845457 has 4 divisors (see below), whose sum is σ = 639635940. Its totient is φ = 638054976.

The previous prime is 638845399. The next prime is 638845463. The reversal of 638845457 is 754548836.

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 406465921 + 232379536 = 20161^2 + 15244^2 .

It is a cyclic number.

It is not a de Polignac number, because 638845457 - 2²² = 634651153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638805457) 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, 394028 + ... + 395645.

It is an arithmetic number, because the mean of its divisors is an integer number (159908985).

Almost surely, 2^638845457 is an apocalyptic number.

It is an amenable number.

638845457 is a deficient number, since it is larger than the sum of its proper divisors (790483).

638845457 is an equidigital number, since it uses as much as digits as its factorization.

638845457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790482.

The product of its digits is 3225600, while the sum is 50.

The square root of 638845457 is about 25275.3923213864. The cubic root of 638845457 is about 861.2553583631.

The spelling of 638845457 in words is "six hundred thirty-eight million, eight hundred forty-five thousand, four hundred fifty-seven".