13287721 has 16 divisors (see below), whose sum is σ = 14376960. Its totient is φ = 12252240.

The previous prime is 13287697. The next prime is 13287737. The reversal of 13287721 is 12778231.

It is a cyclic number.

It is not a de Polignac number, because 13287721 - 2¹³ = 13279529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13288721) 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, 128956 + ... + 129058.

It is an arithmetic number, because the mean of its divisors is an integer number (898560).

Almost surely, 2^13287721 is an apocalyptic number.

It is an amenable number.

13287721 is a deficient number, since it is larger than the sum of its proper divisors (1089239).

13287721 is a wasteful number, since it uses less digits than its factorization.

13287721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 276.

The product of its digits is 4704, while the sum is 31.

The square root of 13287721 is about 3645.2326400382. The cubic root of 13287721 is about 236.8555143710.

The spelling of 13287721 in words is "thirteen million, two hundred eighty-seven thousand, seven hundred twenty-one".