638776 has 8 divisors (see below), whose sum is σ = 1197720. Its totient is φ = 319384.

The previous prime is 638767. The next prime is 638801. The reversal of 638776 is 677836.

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

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, 39916 + ... + 39931.

It is an arithmetic number, because the mean of its divisors is an integer number (149715).

2⁶³⁸⁷⁷⁶ is an apocalyptic number.

It is an amenable number.

638776 is a deficient number, since it is larger than the sum of its proper divisors (558944).

638776 is a wasteful number, since it uses less digits than its factorization.

638776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79853 (or 79849 counting only the distinct ones).

The product of its digits is 42336, while the sum is 37.

The square root of 638776 is about 799.2346338842. The cubic root of 638776 is about 86.1224144564.

Subtracting 638776 from its reverse (677836), we obtain a triangular number (39060 = T₂₇₉).

The spelling of 638776 in words is "six hundred thirty-eight thousand, seven hundred seventy-six".