638289491 has 8 divisors (see below), whose sum is σ = 761190144. Its totient is φ = 523317960.

The previous prime is 638289461. The next prime is 638289493. The reversal of 638289491 is 194982836.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638289491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638289493) 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, 1982105 + ... + 1982426.

It is an arithmetic number, because the mean of its divisors is an integer number (95148768).

Almost surely, 2^638289491 is an apocalyptic number.

638289491 is a deficient number, since it is larger than the sum of its proper divisors (122900653).

638289491 is a wasteful number, since it uses less digits than its factorization.

638289491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3964561.

The product of its digits is 746496, while the sum is 50.

The square root of 638289491 is about 25264.3917599455. The cubic root of 638289491 is about 861.0054452000.

The spelling of 638289491 in words is "six hundred thirty-eight million, two hundred eighty-nine thousand, four hundred ninety-one".