638641641 has 8 divisors (see below), whose sum is σ = 928933344. Its totient is φ = 387055520.

The previous prime is 638641603. The next prime is 638641651. The reversal of 638641641 is 146146836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 638641641 - 2¹⁰ = 638640617 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 638641641.

It is not an unprimeable number, because it can be changed into a prime (638641651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9676356 + ... + 9676421.

It is an arithmetic number, because the mean of its divisors is an integer number (116116668).

Almost surely, 2^638641641 is an apocalyptic number.

It is an amenable number.

638641641 is a deficient number, since it is larger than the sum of its proper divisors (290291703).

638641641 is a wasteful number, since it uses less digits than its factorization.

638641641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19352791.

The product of its digits is 82944, while the sum is 39.

The square root of 638641641 is about 25271.3600939878. The cubic root of 638641641 is about 861.1637575483.

The spelling of 638641641 in words is "six hundred thirty-eight million, six hundred forty-one thousand, six hundred forty-one".