16205621 has 2 divisors, whose sum is σ = 16205622. Its totient is φ = 16205620.

The previous prime is 16205611. The next prime is 16205627. The reversal of 16205621 is 12650261.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9523396 + 6682225 = 3086^2 + 2585^2 .

It is a cyclic number.

It is not a de Polignac number, because 16205621 - 2²² = 12011317 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16205627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8102810 + 8102811.

It is an arithmetic number, because the mean of its divisors is an integer number (8102811).

Almost surely, 2^16205621 is an apocalyptic number.

It is an amenable number.

16205621 is a deficient number, since it is larger than the sum of its proper divisors (1).

16205621 is an equidigital number, since it uses as much as digits as its factorization.

16205621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 16205621 is about 4025.6205732781. The cubic root of 16205621 is about 253.0590612374.

Adding to 16205621 its reverse (12650261), we get a palindrome (28855882).

The spelling of 16205621 in words is "sixteen million, two hundred five thousand, six hundred twenty-one".