15226721 has 8 divisors (see below), whose sum is σ = 15725160. Its totient is φ = 14732928.

The previous prime is 15226699. The next prime is 15226723. The reversal of 15226721 is 12762251.

15226721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 12780625 + 2446096 = 3575^2 + 1564^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15226721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15226723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6245 + ... + 8333.

It is an arithmetic number, because the mean of its divisors is an integer number (1965645).

Almost surely, 2^15226721 is an apocalyptic number.

It is an amenable number.

15226721 is a deficient number, since it is larger than the sum of its proper divisors (498439).

15226721 is a wasteful number, since it uses less digits than its factorization.

15226721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2323.

The product of its digits is 1680, while the sum is 26.

The square root of 15226721 is about 3902.1431291023. The cubic root of 15226721 is about 247.8575371950.

Adding to 15226721 its reverse (12762251), we get a palindrome (27988972).

The spelling of 15226721 in words is "fifteen million, two hundred twenty-six thousand, seven hundred twenty-one".