23220561 has 48 divisors (see below), whose sum is σ = 40219200. Its totient is φ = 11797632.

The previous prime is 23220551. The next prime is 23220563. The reversal of 23220561 is 16502232.

23220561 = T₇₈ + T₇₉ + ... + T₅₁₈.

It is not a de Polignac number, because 23220561 - 2⁵ = 23220529 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23220563) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 55210 + ... + 55628.

It is an arithmetic number, because the mean of its divisors is an integer number (837900).

Almost surely, 2^23220561 is an apocalyptic number.

23220561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

23220561 is a deficient number, since it is larger than the sum of its proper divisors (16998639).

23220561 is a wasteful number, since it uses less digits than its factorization.

23220561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478 (or 471 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 23220561 is about 4818.7717314685. The cubic root of 23220561 is about 285.2928599329.

Adding to 23220561 its reverse (16502232), we get a palindrome (39722793).

The spelling of 23220561 in words is "twenty-three million, two hundred twenty thousand, five hundred sixty-one".