638863892 has 6 divisors (see below), whose sum is σ = 1118011818. Its totient is φ = 319431944.

The previous prime is 638863889. The next prime is 638863949. The reversal of 638863892 is 298368836.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 536570896 + 102292996 = 23164^2 + 10114^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79857983 + ... + 79857990.

It is an arithmetic number, because the mean of its divisors is an integer number (186335303).

Almost surely, 2^638863892 is an apocalyptic number.

It is an amenable number.

638863892 is a deficient number, since it is larger than the sum of its proper divisors (479147926).

638863892 is a wasteful number, since it uses less digits than its factorization.

638863892 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159715977 (or 159715975 counting only the distinct ones).

The product of its digits is 2985984, while the sum is 53.

The square root of 638863892 is about 25275.7570015222. The cubic root of 638863892 is about 861.2636426253.

The spelling of 638863892 in words is "six hundred thirty-eight million, eight hundred sixty-three thousand, eight hundred ninety-two".