638642835 has 12 divisors (see below), whose sum is σ = 1106980992. Its totient is φ = 340609488.

The previous prime is 638642827. The next prime is 638642869. The reversal of 638642835 is 538246836.

It is a happy number.

638642835 is a `hidden beast` number, since 638 + 6 + 4 + 2 + 8 + 3 + 5 = 666.

It is not a de Polignac number, because 638642835 - 2³ = 638642827 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 14192063 = 638642835 / (6 + 3 + 8 + 6 + 4 + 2 + 8 + 3 + 5).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 7095987 + ... + 7096076.

It is an arithmetic number, because the mean of its divisors is an integer number (92248416).

Almost surely, 2^638642835 is an apocalyptic number.

638642835 is a deficient number, since it is larger than the sum of its proper divisors (468338157).

638642835 is a wasteful number, since it uses less digits than its factorization.

638642835 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14192074 (or 14192071 counting only the distinct ones).

The product of its digits is 829440, while the sum is 45.

The square root of 638642835 is about 25271.3837175569. The cubic root of 638642835 is about 861.1642942233.

The spelling of 638642835 in words is "six hundred thirty-eight million, six hundred forty-two thousand, eight hundred thirty-five".