16531985 has 4 divisors (see below), whose sum is σ = 19838388. Its totient is φ = 13225584.

The previous prime is 16531969. The next prime is 16531987. The reversal of 16531985 is 58913561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58913561 = 7 ⋅8416223.

It can be written as a sum of positive squares in 2 ways, for example, as 3972049 + 12559936 = 1993^2 + 3544^2 .

It is a cyclic number.

It is not a de Polignac number, because 16531985 - 2⁴ = 16531969 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (16531987) 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, 1653194 + ... + 1653203.

It is an arithmetic number, because the mean of its divisors is an integer number (4959597).

Almost surely, 2^16531985 is an apocalyptic number.

It is an amenable number.

16531985 is a deficient number, since it is larger than the sum of its proper divisors (3306403).

16531985 is an equidigital number, since it uses as much as digits as its factorization.

16531985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3306402.

The product of its digits is 32400, while the sum is 38.

The square root of 16531985 is about 4065.9543775109. The cubic root of 16531985 is about 254.7465635284.

The spelling of 16531985 in words is "sixteen million, five hundred thirty-one thousand, nine hundred eighty-five".