13085721 has 24 divisors (see below), whose sum is σ = 20797920. Its totient is φ = 7862400.

The previous prime is 13085713. The next prime is 13085729. The reversal of 13085721 is 12758031.

13085721 is digitally balanced in base 2, base 3 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (13085713) and next prime (13085729).

It is not a de Polignac number, because 13085721 - 2³ = 13085713 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13085729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12465 + ... + 13473.

It is an arithmetic number, because the mean of its divisors is an integer number (866580).

Almost surely, 2^13085721 is an apocalyptic number.

13085721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13085721 is a deficient number, since it is larger than the sum of its proper divisors (7712199).

13085721 is a wasteful number, since it uses less digits than its factorization.

13085721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1157 (or 1154 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 13085721 is about 3617.4191075959. The cubic root of 13085721 is about 235.6491542992.

The spelling of 13085721 in words is "thirteen million, eighty-five thousand, seven hundred twenty-one".