15552221 has 4 divisors (see below), whose sum is σ = 15564192. Its totient is φ = 15540252.

The previous prime is 15552217. The next prime is 15552227. The reversal of 15552221 is 12225551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 15552221 - 2² = 15552217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15552227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3761 + ... + 6726.

It is an arithmetic number, because the mean of its divisors is an integer number (3891048).

Almost surely, 2^15552221 is an apocalyptic number.

It is an amenable number.

15552221 is a deficient number, since it is larger than the sum of its proper divisors (11971).

15552221 is a wasteful number, since it uses less digits than its factorization.

15552221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11970.

The product of its digits is 1000, while the sum is 23.

The square root of 15552221 is about 3943.6304340037. The cubic root of 15552221 is about 249.6112411128.

Adding to 15552221 its reverse (12225551), we get a palindrome (27777772).

The spelling of 15552221 in words is "fifteen million, five hundred fifty-two thousand, two hundred twenty-one".