16565561 has 2 divisors, whose sum is σ = 16565562. Its totient is φ = 16565560.

The previous prime is 16565551. The next prime is 16565569. The reversal of 16565561 is 16556561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8970025 + 7595536 = 2995^2 + 2756^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16565561 is a prime.

It is a super-2 number, since 2×16565561² = 548835622489442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (16565569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8282780 + 8282781.

It is an arithmetic number, because the mean of its divisors is an integer number (8282781).

Almost surely, 2^16565561 is an apocalyptic number.

It is an amenable number.

16565561 is a deficient number, since it is larger than the sum of its proper divisors (1).

16565561 is an equidigital number, since it uses as much as digits as its factorization.

16565561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27000, while the sum is 35.

The square root of 16565561 is about 4070.0812031211. The cubic root of 16565561 is about 254.9189079582.

The spelling of 16565561 in words is "sixteen million, five hundred sixty-five thousand, five hundred sixty-one".