15716221 has 2 divisors, whose sum is σ = 15716222. Its totient is φ = 15716220.

The previous prime is 15716219. The next prime is 15716273. The reversal of 15716221 is 12261751.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12425625 + 3290596 = 3525^2 + 1814^2 .

It is a cyclic number.

It is not a de Polignac number, because 15716221 - 2¹ = 15716219 is a prime.

Together with 15716219, 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 (15710221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7858110 + 7858111.

It is an arithmetic number, because the mean of its divisors is an integer number (7858111).

Almost surely, 2^15716221 is an apocalyptic number.

It is an amenable number.

15716221 is a deficient number, since it is larger than the sum of its proper divisors (1).

15716221 is an equidigital number, since it uses as much as digits as its factorization.

15716221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 840, while the sum is 25.

The square root of 15716221 is about 3964.3689283416. The cubic root of 15716221 is about 250.4855682832.

Adding to 15716221 its reverse (12261751), we get a palindrome (27977972).

The spelling of 15716221 in words is "fifteen million, seven hundred sixteen thousand, two hundred twenty-one".