561808181 has 4 divisors (see below), whose sum is σ = 612881664. Its totient is φ = 510734700.

The previous prime is 561808153. The next prime is 561808183. The reversal of 561808181 is 181808165.

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 a de Polignac number, because none of the positive numbers 2^k-561808181 is a prime.

It is a super-2 number, since 2×561808181² = 631256864477057522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561808183) 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, 25536725 + ... + 25536746.

It is an arithmetic number, because the mean of its divisors is an integer number (153220416).

Almost surely, 2^561808181 is an apocalyptic number.

It is an amenable number.

561808181 is a deficient number, since it is larger than the sum of its proper divisors (51073483).

561808181 is a wasteful number, since it uses less digits than its factorization.

561808181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51073482.

The product of its (nonzero) digits is 15360, while the sum is 38.

The square root of 561808181 is about 23702.4931389084. The cubic root of 561808181 is about 825.1432532385.

The spelling of 561808181 in words is "five hundred sixty-one million, eight hundred eight thousand, one hundred eighty-one".