16535581 has 2 divisors, whose sum is σ = 16535582. Its totient is φ = 16535580.

The previous prime is 16535537. The next prime is 16535593. The reversal of 16535581 is 18553561.

16535581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14699556 + 1836025 = 3834^2 + 1355^2 .

It is a cyclic number.

It is not a de Polignac number, because 16535581 - 2¹⁵ = 16502813 is a prime.

It is a super-2 number, since 2×16535581² = 546850878015122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16535501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8267790 + 8267791.

It is an arithmetic number, because the mean of its divisors is an integer number (8267791).

Almost surely, 2^16535581 is an apocalyptic number.

It is an amenable number.

16535581 is a deficient number, since it is larger than the sum of its proper divisors (1).

16535581 is an equidigital number, since it uses as much as digits as its factorization.

16535581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18000, while the sum is 34.

The square root of 16535581 is about 4066.3965620682. The cubic root of 16535581 is about 254.7650328215.

The spelling of 16535581 in words is "sixteen million, five hundred thirty-five thousand, five hundred eighty-one".