13285721 has 4 divisors (see below), whose sum is σ = 14067252. Its totient is φ = 12504192.

The previous prime is 13285717. The next prime is 13285757. The reversal of 13285721 is 12758231.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4044121 + 9241600 = 2011^2 + 3040^2 .

It is a cyclic number.

It is not a de Polignac number, because 13285721 - 2² = 13285717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13285711) 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 3 ways as a sum of consecutive naturals, for example, 390740 + ... + 390773.

It is an arithmetic number, because the mean of its divisors is an integer number (3516813).

Almost surely, 2^13285721 is an apocalyptic number.

It is an amenable number.

13285721 is a deficient number, since it is larger than the sum of its proper divisors (781531).

13285721 is an equidigital number, since it uses as much as digits as its factorization.

13285721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 781530.

The product of its digits is 3360, while the sum is 29.

The square root of 13285721 is about 3644.9582988012. The cubic root of 13285721 is about 236.8436303467.

The spelling of 13285721 in words is "thirteen million, two hundred eighty-five thousand, seven hundred twenty-one".