23309561 has 12 divisors (see below), whose sum is σ = 26972400. Its totient is φ = 20073240.

The previous prime is 23309537. The next prime is 23309563. The reversal of 23309561 is 16590332.

It is not a de Polignac number, because 23309561 - 2¹⁸ = 23047417 is a prime.

It is a super-4 number, since 4×23309561⁴ (a number of 31 digits) contains 4444 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (23309563) 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, 2771 + ... + 7368.

It is an arithmetic number, because the mean of its divisors is an integer number (2247700).

Almost surely, 2^23309561 is an apocalyptic number.

It is an amenable number.

23309561 is a deficient number, since it is larger than the sum of its proper divisors (3662839).

23309561 is a wasteful number, since it uses less digits than its factorization.

23309561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10180 (or 10169 counting only the distinct ones).

The product of its (nonzero) digits is 4860, while the sum is 29.

The square root of 23309561 is about 4827.9976180607. The cubic root of 23309561 is about 285.6568863622.

Adding to 23309561 its reverse (16590332), we get a palindrome (39899893).

The spelling of 23309561 in words is "twenty-three million, three hundred nine thousand, five hundred sixty-one".