16331521 has 2 divisors, whose sum is σ = 16331522. Its totient is φ = 16331520.

The previous prime is 16331519. The next prime is 16331531. The reversal of 16331521 is 12513361.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13771521 + 2560000 = 3711^2 + 1600^2 .

It is a cyclic number.

It is not a de Polignac number, because 16331521 - 2¹ = 16331519 is a prime.

Together with 16331519, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 16331492 and 16331501.

It is not a weakly prime, because it can be changed into another prime (16331501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8165760 + 8165761.

It is an arithmetic number, because the mean of its divisors is an integer number (8165761).

Almost surely, 2^16331521 is an apocalyptic number.

It is an amenable number.

16331521 is a deficient number, since it is larger than the sum of its proper divisors (1).

16331521 is an equidigital number, since it uses as much as digits as its factorization.

16331521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 540, while the sum is 22.

The square root of 16331521 is about 4041.2276600063. The cubic root of 16331521 is about 253.7127024217.

Adding to 16331521 its reverse (12513361), we get a palindrome (28844882).

It can be divided in two parts, 163 and 31521, that added together give a square (31684 = 178²).

The spelling of 16331521 in words is "sixteen million, three hundred thirty-one thousand, five hundred twenty-one".