15481721 has 4 divisors (see below), whose sum is σ = 15513744. Its totient is φ = 15449700.

The previous prime is 15481663. The next prime is 15481727. The reversal of 15481721 is 12718451.

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 15481721 - 2⁶ = 15481657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15481727) 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, 15275 + ... + 16256.

It is an arithmetic number, because the mean of its divisors is an integer number (3878436).

Almost surely, 2^15481721 is an apocalyptic number.

It is an amenable number.

15481721 is a deficient number, since it is larger than the sum of its proper divisors (32023).

15481721 is an equidigital number, since it uses as much as digits as its factorization.

15481721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32022.

The product of its digits is 2240, while the sum is 29.

The square root of 15481721 is about 3934.6818168691. The cubic root of 15481721 is about 249.2334976316.

The spelling of 15481721 in words is "fifteen million, four hundred eighty-one thousand, seven hundred twenty-one".