15120721 has 16 divisors (see below), whose sum is σ = 18938880. Its totient is φ = 11728080.

The previous prime is 15120673. The next prime is 15120727. The reversal of 15120721 is 12702151.

It is not a de Polignac number, because 15120721 - 2¹¹ = 15118673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15120727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27370 + ... + 27916.

It is an arithmetic number, because the mean of its divisors is an integer number (1183680).

Almost surely, 2^15120721 is an apocalyptic number.

15120721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

15120721 is a deficient number, since it is larger than the sum of its proper divisors (3818159).

15120721 is a wasteful number, since it uses less digits than its factorization.

15120721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 15120721 is about 3888.5371285356. The cubic root of 15120721 is about 247.2810484111.

Adding to 15120721 its reverse (12702151), we get a palindrome (27822872).

The spelling of 15120721 in words is "fifteen million, one hundred twenty thousand, seven hundred twenty-one".