638771069 has 2 divisors, whose sum is σ = 638771070. Its totient is φ = 638771068.

The previous prime is 638771009. The next prime is 638771117. The reversal of 638771069 is 960177836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 587820025 + 50951044 = 24245^2 + 7138^2 .

It is a cyclic number.

It is not a de Polignac number, because 638771069 - 2⁸ = 638770813 is a prime.

It is a super-2 number, since 2×638771069² = 816056957182805522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638771009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319385534 + 319385535.

It is an arithmetic number, because the mean of its divisors is an integer number (319385535).

Almost surely, 2^638771069 is an apocalyptic number.

It is an amenable number.

638771069 is a deficient number, since it is larger than the sum of its proper divisors (1).

638771069 is an equidigital number, since it uses as much as digits as its factorization.

638771069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 381024, while the sum is 47.

The square root of 638771069 is about 25273.9207286879. The cubic root of 638771069 is about 861.2219284990.

It can be divided in two parts, 63877 and 1069, that added together give a palindrome (64946).

The spelling of 638771069 in words is "six hundred thirty-eight million, seven hundred seventy-one thousand, sixty-nine".