638959409 has 4 divisors (see below), whose sum is σ = 697046640. Its totient is φ = 580872180.

The previous prime is 638959393. The next prime is 638959463. The reversal of 638959409 is 904959836.

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 638959409 - 2⁴ = 638959393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638959469) 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, 29043599 + ... + 29043620.

It is an arithmetic number, because the mean of its divisors is an integer number (174261660).

Almost surely, 2^638959409 is an apocalyptic number.

It is an amenable number.

638959409 is a deficient number, since it is larger than the sum of its proper divisors (58087231).

638959409 is a wasteful number, since it uses less digits than its factorization.

638959409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58087230.

The product of its (nonzero) digits is 2099520, while the sum is 53.

The square root of 638959409 is about 25277.6464292070. The cubic root of 638959409 is about 861.3065632019.

The spelling of 638959409 in words is "six hundred thirty-eight million, nine hundred fifty-nine thousand, four hundred nine".