23381561 has 4 divisors (see below), whose sum is σ = 26721792. Its totient is φ = 20041332.

The previous prime is 23381537. The next prime is 23381563. The reversal of 23381561 is 16518332.

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 not a de Polignac number, because 23381561 - 2⁶ = 23381497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23381563) 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, 1670105 + ... + 1670118.

It is an arithmetic number, because the mean of its divisors is an integer number (6680448).

Almost surely, 2^23381561 is an apocalyptic number.

It is an amenable number.

23381561 is a deficient number, since it is larger than the sum of its proper divisors (3340231).

23381561 is an equidigital number, since it uses as much as digits as its factorization.

23381561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3340230.

The product of its digits is 4320, while the sum is 29.

The square root of 23381561 is about 4835.4483763142. The cubic root of 23381561 is about 285.9507022142.

Adding to 23381561 its reverse (16518332), we get a palindrome (39899893).

The spelling of 23381561 in words is "twenty-three million, three hundred eighty-one thousand, five hundred sixty-one".