16561535 has 4 divisors (see below), whose sum is σ = 19873848. Its totient is φ = 13249224.

The previous prime is 16561513. The next prime is 16561543. The reversal of 16561535 is 53516561.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 16561535 - 2¹⁸ = 16299391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1656149 + ... + 1656158.

It is an arithmetic number, because the mean of its divisors is an integer number (4968462).

Almost surely, 2^16561535 is an apocalyptic number.

16561535 is a deficient number, since it is larger than the sum of its proper divisors (3312313).

16561535 is an equidigital number, since it uses as much as digits as its factorization.

16561535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3312312.

The product of its digits is 13500, while the sum is 32.

The square root of 16561535 is about 4069.5865883404. The cubic root of 16561535 is about 254.8982549365.

The spelling of 16561535 in words is "sixteen million, five hundred sixty-one thousand, five hundred thirty-five".