638276440 has 16 divisors (see below), whose sum is σ = 1436122080. Its totient is φ = 255310560.

The previous prime is 638276413. The next prime is 638276447. The reversal of 638276440 is 44672836.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (40), and also a Moran number because the ratio is a prime number: 15956911 = 638276440 / (6 + 3 + 8 + 2 + 7 + 6 + 4 + 4 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 638276393 and 638276402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638276447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7978416 + ... + 7978495.

It is an arithmetic number, because the mean of its divisors is an integer number (89757630).

Almost surely, 2^638276440 is an apocalyptic number.

It is an amenable number.

638276440 is an abundant number, since it is smaller than the sum of its proper divisors (797845640).

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

638276440 is a wasteful number, since it uses less digits than its factorization.

638276440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15956922 (or 15956918 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 40.

The square root of 638276440 is about 25264.1334701984. The cubic root of 638276440 is about 860.9995768812. Note that the first 3 decimals are identical.

The spelling of 638276440 in words is "six hundred thirty-eight million, two hundred seventy-six thousand, four hundred forty".