638411869 has 2 divisors, whose sum is σ = 638411870. Its totient is φ = 638411868.

The previous prime is 638411827. The next prime is 638411903. The reversal of 638411869 is 968114836.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 464962969 + 173448900 = 21563^2 + 13170^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638411869 is a prime.

It is a super-2 number, since 2×638411869² = 815139428960146322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638411569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319205934 + 319205935.

It is an arithmetic number, because the mean of its divisors is an integer number (319205935).

Almost surely, 2^638411869 is an apocalyptic number.

It is an amenable number.

638411869 is a deficient number, since it is larger than the sum of its proper divisors (1).

638411869 is an equidigital number, since it uses as much as digits as its factorization.

638411869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 46.

The square root of 638411869 is about 25266.8135901621. The cubic root of 638411869 is about 861.0604679823.

The spelling of 638411869 in words is "six hundred thirty-eight million, four hundred eleven thousand, eight hundred sixty-nine".