638079978 has 16 divisors (see below), whose sum is σ = 1276512480. Its totient is φ = 212634576.

The previous prime is 638079973. The next prime is 638079979. The reversal of 638079978 is 879970836.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (638079973) 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 7 ways as a sum of consecutive naturals, for example, 12801 + ... + 37947.

It is an arithmetic number, because the mean of its divisors is an integer number (79782030).

Almost surely, 2^638079978 is an apocalyptic number.

638079978 is an abundant number, since it is smaller than the sum of its proper divisors (638432502).

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

638079978 is a wasteful number, since it uses less digits than its factorization.

638079978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29381.

The product of its (nonzero) digits is 4572288, while the sum is 57.

The square root of 638079978 is about 25260.2450106882. The cubic root of 638079978 is about 860.9112290294.

The spelling of 638079978 in words is "six hundred thirty-eight million, seventy-nine thousand, nine hundred seventy-eight".