16623561 has 4 divisors (see below), whose sum is σ = 22164752. Its totient is φ = 11082372.

The previous prime is 16623559. The next prime is 16623577. The reversal of 16623561 is 16532661.

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 not a de Polignac number, because 16623561 - 2¹ = 16623559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16623511) 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, 2770591 + ... + 2770596.

It is an arithmetic number, because the mean of its divisors is an integer number (5541188).

Almost surely, 2^16623561 is an apocalyptic number.

It is an amenable number.

16623561 is a deficient number, since it is larger than the sum of its proper divisors (5541191).

16623561 is an equidigital number, since it uses as much as digits as its factorization.

16623561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5541190.

The product of its digits is 6480, while the sum is 30.

The square root of 16623561 is about 4077.2001422545. The cubic root of 16623561 is about 255.2160721478.

The spelling of 16623561 in words is "sixteen million, six hundred twenty-three thousand, five hundred sixty-one".