15216661 has 2 divisors, whose sum is σ = 15216662. Its totient is φ = 15216660.

The previous prime is 15216659. The next prime is 15216679. The reversal of 15216661 is 16661251.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14485636 + 731025 = 3806^2 + 855^2 .

It is an emirp because it is prime and its reverse (16661251) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15216661 - 2¹ = 15216659 is a prime.

Together with 15216659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15216601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7608330 + 7608331.

It is an arithmetic number, because the mean of its divisors is an integer number (7608331).

Almost surely, 2^15216661 is an apocalyptic number.

It is an amenable number.

15216661 is a deficient number, since it is larger than the sum of its proper divisors (1).

15216661 is an equidigital number, since it uses as much as digits as its factorization.

15216661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2160, while the sum is 28.

The square root of 15216661 is about 3900.8538808830. The cubic root of 15216661 is about 247.8029402762.

The spelling of 15216661 in words is "fifteen million, two hundred sixteen thousand, six hundred sixty-one".