561638238 has 64 divisors (see below), whose sum is σ = 1304916480. Its totient is φ = 157842432.

The previous prime is 561638227. The next prime is 561638243. The reversal of 561638238 is 832836165.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 561638238.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1296870 + ... + 1297302.

It is an arithmetic number, because the mean of its divisors is an integer number (20389320).

Almost surely, 2^561638238 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 561638238, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (652458240).

561638238 is an abundant number, since it is smaller than the sum of its proper divisors (743278242).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

561638238 is a wasteful number, since it uses less digits than its factorization.

561638238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 881.

The product of its digits is 207360, while the sum is 42.

The square root of 561638238 is about 23698.9079495238. The cubic root of 561638238 is about 825.0600448492.

The spelling of 561638238 in words is "five hundred sixty-one million, six hundred thirty-eight thousand, two hundred thirty-eight".