638723280 has 80 divisors (see below), whose sum is σ = 2132363520. Its totient is φ = 157223424.

The previous prime is 638723273. The next prime is 638723311. The reversal of 638723280 is 82327836.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99240 + ... + 105479.

It is an arithmetic number, because the mean of its divisors is an integer number (26654544).

Almost surely, 2^638723280 is an apocalyptic number.

638723280 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

638723280 is an abundant number, since it is smaller than the sum of its proper divisors (1493640240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638723280 is a wasteful number, since it uses less digits than its factorization.

638723280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204748 (or 204742 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 39.

The square root of 638723280 is about 25272.9752898229. The cubic root of 638723280 is about 861.2004508194.

The spelling of 638723280 in words is "six hundred thirty-eight million, seven hundred twenty-three thousand, two hundred eighty".