23551561 has 12 divisors (see below), whose sum is σ = 26334000. Its totient is φ = 21041240.

The previous prime is 23551531. The next prime is 23551601. The reversal of 23551561 is 16515532.

It is not a de Polignac number, because 23551561 - 2⁵ = 23551529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (23551501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5490 + ... + 8788.

It is an arithmetic number, because the mean of its divisors is an integer number (2194500).

Almost surely, 2^23551561 is an apocalyptic number.

It is an amenable number.

23551561 is a deficient number, since it is larger than the sum of its proper divisors (2782439).

23551561 is a wasteful number, since it uses less digits than its factorization.

23551561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3380 (or 3369 counting only the distinct ones).

The product of its digits is 4500, while the sum is 28.

The square root of 23551561 is about 4852.9950546029. The cubic root of 23551561 is about 286.6420486942.

It can be divided in two parts, 2355 and 1561, that added together give a triangular number (3916 = T₈₈).

The spelling of 23551561 in words is "twenty-three million, five hundred fifty-one thousand, five hundred sixty-one".