638928001 has 4 divisors (see below), whose sum is σ = 639266004. Its totient is φ = 638590000.

The previous prime is 638927981. The next prime is 638928007. The reversal of 638928001 is 100829836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 331276401 + 307651600 = 18201^2 + 17540^2 .

It is a cyclic number.

It is not a de Polignac number, because 638928001 - 2²¹ = 636830849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638928007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166150 + ... + 169951.

It is an arithmetic number, because the mean of its divisors is an integer number (159816501).

Almost surely, 2^638928001 is an apocalyptic number.

It is an amenable number.

638928001 is a deficient number, since it is larger than the sum of its proper divisors (338003).

638928001 is a wasteful number, since it uses less digits than its factorization.

638928001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338002.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 638928001 is about 25277.0251612012. The cubic root of 638928001 is about 861.2924504850.

The spelling of 638928001 in words is "six hundred thirty-eight million, nine hundred twenty-eight thousand, one".