638235409 has 16 divisors (see below), whose sum is σ = 753831936. Its totient is φ = 528786000.

The previous prime is 638235373. The next prime is 638235427. The reversal of 638235409 is 904532836.

It is a cyclic number.

It is not a de Polignac number, because 638235409 - 2⁹ = 638234897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638232409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 313854 + ... + 315880.

It is an arithmetic number, because the mean of its divisors is an integer number (47114496).

Almost surely, 2^638235409 is an apocalyptic number.

It is an amenable number.

638235409 is a deficient number, since it is larger than the sum of its proper divisors (115596527).

638235409 is a wasteful number, since it uses less digits than its factorization.

638235409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3516.

The product of its (nonzero) digits is 155520, while the sum is 40.

The square root of 638235409 is about 25263.3214166309. The cubic root of 638235409 is about 860.9811269702.

The spelling of 638235409 in words is "six hundred thirty-eight million, two hundred thirty-five thousand, four hundred nine".