638925987 has 16 divisors (see below), whose sum is σ = 977050880. Its totient is φ = 363807072.

The previous prime is 638925983. The next prime is 638926007. The reversal of 638925987 is 789529836.

It is not a de Polignac number, because 638925987 - 2² = 638925983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638925983) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47812 + ... + 59697.

It is an arithmetic number, because the mean of its divisors is an integer number (61065680).

Almost surely, 2^638925987 is an apocalyptic number.

638925987 is a deficient number, since it is larger than the sum of its proper divisors (338124893).

638925987 is a wasteful number, since it uses less digits than its factorization.

638925987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107802.

The product of its digits is 6531840, while the sum is 57.

The square root of 638925987 is about 25276.9853226211. The cubic root of 638925987 is about 861.2915455083.

The spelling of 638925987 in words is "six hundred thirty-eight million, nine hundred twenty-five thousand, nine hundred eighty-seven".