16511561 has 16 divisors (see below), whose sum is σ = 19063296. Its totient is φ = 14160000.

The previous prime is 16511557. The next prime is 16511569.

16511561 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 16511561 - 2² = 16511557 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16511561.

It is not an unprimeable number, because it can be changed into a prime (16511569) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13391 + ... + 14571.

It is an arithmetic number, because the mean of its divisors is an integer number (1191456).

Almost surely, 2^16511561 is an apocalyptic number.

16511561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16511561 is a deficient number, since it is larger than the sum of its proper divisors (2551735).

16511561 is a wasteful number, since it uses less digits than its factorization.

16511561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1264.

The product of its digits is 900, while the sum is 26.

The square root of 16511561 is about 4063.4420138597. The cubic root of 16511561 is about 254.6416136812.

The spelling of 16511561 in words is "sixteen million, five hundred eleven thousand, five hundred sixty-one".