15534721 has 2 divisors, whose sum is σ = 15534722. Its totient is φ = 15534720.

The previous prime is 15534713. The next prime is 15534731. The reversal of 15534721 is 12743551.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9678321 + 5856400 = 3111^2 + 2420^2 .

It is an emirp because it is prime and its reverse (12743551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15534721 - 2³ = 15534713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 15534721.

It is not a weakly prime, because it can be changed into another prime (15534731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7767360 + 7767361.

It is an arithmetic number, because the mean of its divisors is an integer number (7767361).

Almost surely, 2^15534721 is an apocalyptic number.

It is an amenable number.

15534721 is a deficient number, since it is larger than the sum of its proper divisors (1).

15534721 is an equidigital number, since it uses as much as digits as its factorization.

15534721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4200, while the sum is 28.

The square root of 15534721 is about 3941.4110417463. The cubic root of 15534721 is about 249.5175816891.

The spelling of 15534721 in words is "fifteen million, five hundred thirty-four thousand, seven hundred twenty-one".