201115561 has 4 divisors (see below), whose sum is σ = 201344724. Its totient is φ = 200886400.

The previous prime is 201115553. The next prime is 201115567. The reversal of 201115561 is 165511102.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 44089600 + 157025961 = 6640^2 + 12531^2 .

It is a cyclic number.

It is not a de Polignac number, because 201115561 - 2³ = 201115553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201115567) 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, 113260 + ... + 115021.

It is an arithmetic number, because the mean of its divisors is an integer number (50336181).

Almost surely, 2^201115561 is an apocalyptic number.

It is an amenable number.

201115561 is a deficient number, since it is larger than the sum of its proper divisors (229163).

201115561 is an equidigital number, since it uses as much as digits as its factorization.

201115561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229162.

The product of its (nonzero) digits is 300, while the sum is 22.

The square root of 201115561 is about 14181.5218153765. The cubic root of 201115561 is about 585.8888390063. Note that the first 4 decimals are identical.

Adding to 201115561 its reverse (165511102), we get a palindrome (366626663).

The spelling of 201115561 in words is "two hundred one million, one hundred fifteen thousand, five hundred sixty-one".