13799721 has 16 divisors (see below), whose sum is σ = 19893440. Its totient is φ = 8458560.

The previous prime is 13799713. The next prime is 13799741. The reversal of 13799721 is 12799731.

It is not a de Polignac number, because 13799721 - 2³ = 13799713 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 13799721.

It is not an unprimeable number, because it can be changed into a prime (13799741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12375 + ... + 13443.

It is an arithmetic number, because the mean of its divisors is an integer number (1243340).

Almost surely, 2^13799721 is an apocalyptic number.

13799721 is the 1986-th nonagonal number.

It is an amenable number.

13799721 is a deficient number, since it is larger than the sum of its proper divisors (6093719).

13799721 is a wasteful number, since it uses less digits than its factorization.

13799721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1416.

The product of its digits is 23814, while the sum is 39.

The square root of 13799721 is about 3714.7975718739. The cubic root of 13799721 is about 239.8594141923.

The spelling of 13799721 in words is "thirteen million, seven hundred ninety-nine thousand, seven hundred twenty-one".