638421169 has 4 divisors (see below), whose sum is σ = 639555696. Its totient is φ = 637286644.

The previous prime is 638421151. The next prime is 638421193. The reversal of 638421169 is 961124836.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 638421169 - 2¹¹ = 638419121 is a prime.

It is a super-2 number, since 2×638421169² = 815163178054653122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638421139) 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, 566419 + ... + 567544.

It is an arithmetic number, because the mean of its divisors is an integer number (159888924).

Almost surely, 2^638421169 is an apocalyptic number.

It is an amenable number.

638421169 is a deficient number, since it is larger than the sum of its proper divisors (1134527).

638421169 is a wasteful number, since it uses less digits than its factorization.

638421169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1134526.

The product of its digits is 62208, while the sum is 40.

The square root of 638421169 is about 25266.9976253610. The cubic root of 638421169 is about 861.0646490990.

The spelling of 638421169 in words is "six hundred thirty-eight million, four hundred twenty-one thousand, one hundred sixty-nine".