12987521 has 6 divisors (see below), whose sum is σ = 13160322. Its totient is φ = 12816960.

The previous prime is 12987509. The next prime is 12987523. The reversal of 12987521 is 12578921.

It can be written as a sum of positive squares in only one way, i.e., 10491121 + 2496400 = 3239^2 + 1580^2 .

It is not a de Polignac number, because 12987521 - 2¹⁰ = 12986497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12987523) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5201 + ... + 7281.

It is an arithmetic number, because the mean of its divisors is an integer number (2193387).

Almost surely, 2^12987521 is an apocalyptic number.

12987521 is the 2081-st octagonal number.

It is an amenable number.

12987521 is a deficient number, since it is larger than the sum of its proper divisors (172801).

12987521 is an frugal number, since it uses more digits than its factorization.

12987521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2239 (or 2160 counting only the distinct ones).

The product of its digits is 10080, while the sum is 35.

The square root of 12987521 is about 3603.8203340344. The cubic root of 12987521 is about 235.0582080045.

The spelling of 12987521 in words is "twelve million, nine hundred eighty-seven thousand, five hundred twenty-one".