16653561 has 4 divisors (see below), whose sum is σ = 22204752. Its totient is φ = 11102372.

The previous prime is 16653551. The next prime is 16653619. The reversal of 16653561 is 16535661.

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 16653561 - 2¹¹ = 16651513 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16653551) 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, 2775591 + ... + 2775596.

It is an arithmetic number, because the mean of its divisors is an integer number (5551188).

Almost surely, 2^16653561 is an apocalyptic number.

It is an amenable number.

16653561 is a deficient number, since it is larger than the sum of its proper divisors (5551191).

16653561 is an equidigital number, since it uses as much as digits as its factorization.

16653561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5551190.

The product of its digits is 16200, while the sum is 33.

The square root of 16653561 is about 4080.8774791704. The cubic root of 16653561 is about 255.3695066009.

The spelling of 16653561 in words is "sixteen million, six hundred fifty-three thousand, five hundred sixty-one".