638722693 has 12 divisors (see below), whose sum is σ = 743503212. Its totient is φ = 547108800.

The previous prime is 638722681. The next prime is 638722717. The reversal of 638722693 is 396227836.

It can be written as a sum of positive squares in 2 ways, for example, as 22591009 + 616131684 = 4753^2 + 24822^2 .

It is not a de Polignac number, because 638722693 - 2⁵ = 638722661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638722493) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 89721 + ... + 96577.

It is an arithmetic number, because the mean of its divisors is an integer number (61958601).

Almost surely, 2^638722693 is an apocalyptic number.

It is an amenable number.

638722693 is a deficient number, since it is larger than the sum of its proper divisors (104780519).

638722693 is a wasteful number, since it uses less digits than its factorization.

638722693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8772 (or 8765 counting only the distinct ones).

The product of its digits is 653184, while the sum is 46.

The square root of 638722693 is about 25272.9636766249. The cubic root of 638722693 is about 861.2001869989.

The spelling of 638722693 in words is "six hundred thirty-eight million, seven hundred twenty-two thousand, six hundred ninety-three".