635638401 has 8 divisors (see below), whose sum is σ = 941686560. Its totient is φ = 423758916.

The previous prime is 635638397. The next prime is 635638411. The reversal of 635638401 is 104836536.

It is not a de Polignac number, because 635638401 - 2² = 635638397 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (635638411) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11771055 + ... + 11771108.

It is an arithmetic number, because the mean of its divisors is an integer number (117710820).

Almost surely, 2^635638401 is an apocalyptic number.

It is an amenable number.

635638401 is a deficient number, since it is larger than the sum of its proper divisors (306048159).

635638401 is a wasteful number, since it uses less digits than its factorization.

635638401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23542172 (or 23542166 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 635638401 is about 25211.8702400278. The cubic root of 635638401 is about 859.8117494032.

The spelling of 635638401 in words is "six hundred thirty-five million, six hundred thirty-eight thousand, four hundred one".