16531621 has 2 divisors, whose sum is σ = 16531622. Its totient is φ = 16531620.

The previous prime is 16531597. The next prime is 16531673. The reversal of 16531621 is 12613561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16524225 + 7396 = 4065^2 + 86^2 .

It is an emirp because it is prime and its reverse (12613561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16531621 - 2¹¹ = 16529573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16531321) 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, 8265810 + 8265811.

It is an arithmetic number, because the mean of its divisors is an integer number (8265811).

Almost surely, 2^16531621 is an apocalyptic number.

It is an amenable number.

16531621 is a deficient number, since it is larger than the sum of its proper divisors (1).

16531621 is an equidigital number, since it uses as much as digits as its factorization.

16531621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1080, while the sum is 25.

The square root of 16531621 is about 4065.9096153259. The cubic root of 16531621 is about 254.7446938511.

The spelling of 16531621 in words is "sixteen million, five hundred thirty-one thousand, six hundred twenty-one".