638543421 has 24 divisors (see below), whose sum is σ = 945497696. Its totient is φ = 415044000.

The previous prime is 638543413. The next prime is 638543441. The reversal of 638543421 is 124345836.

It is not a de Polignac number, because 638543421 - 2³ = 638543413 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638543441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 282546 + ... + 284796.

Almost surely, 2^638543421 is an apocalyptic number.

It is an amenable number.

638543421 is a deficient number, since it is larger than the sum of its proper divisors (306954275).

638543421 is a wasteful number, since it uses less digits than its factorization.

638543421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3033 (or 3030 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 638543421 is about 25269.4167126984. The cubic root of 638543421 is about 861.1196076760.

The spelling of 638543421 in words is "six hundred thirty-eight million, five hundred forty-three thousand, four hundred twenty-one".