15372221 has 2 divisors, whose sum is σ = 15372222. Its totient is φ = 15372220.

The previous prime is 15372209. The next prime is 15372223. The reversal of 15372221 is 12227351.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9369721 + 6002500 = 3061^2 + 2450^2 .

It is a cyclic number.

It is not a de Polignac number, because 15372221 - 2⁶ = 15372157 is a prime.

It is a Sophie Germain prime.

Together with 15372223, it forms a pair of twin primes.

It is a Chen 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 (15372223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7686110 + 7686111.

It is an arithmetic number, because the mean of its divisors is an integer number (7686111).

Almost surely, 2^15372221 is an apocalyptic number.

It is an amenable number.

15372221 is a deficient number, since it is larger than the sum of its proper divisors (1).

15372221 is an equidigital number, since it uses as much as digits as its factorization.

15372221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 840, while the sum is 23.

The square root of 15372221 is about 3920.7424041883. The cubic root of 15372221 is about 248.6445091948.

Adding to 15372221 its reverse (12227351), we get a palindrome (27599572).

The spelling of 15372221 in words is "fifteen million, three hundred seventy-two thousand, two hundred twenty-one".