12891521 has 2 divisors, whose sum is σ = 12891522. Its totient is φ = 12891520.

The previous prime is 12891517. The next prime is 12891533. The reversal of 12891521 is 12519821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11316496 + 1575025 = 3364^2 + 1255^2 .

It is a cyclic number.

It is not a de Polignac number, because 12891521 - 2² = 12891517 is a prime.

It is a Chen prime.

It is equal to p₈₄₂₆₈₁ and since 12891521 and 842681 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (12891721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6445760 + 6445761.

It is an arithmetic number, because the mean of its divisors is an integer number (6445761).

Almost surely, 2^12891521 is an apocalyptic number.

It is an amenable number.

12891521 is a deficient number, since it is larger than the sum of its proper divisors (1).

12891521 is an equidigital number, since it uses as much as digits as its factorization.

12891521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 29.

The square root of 12891521 is about 3590.4764307819. The cubic root of 12891521 is about 234.4776143497.

The spelling of 12891521 in words is "twelve million, eight hundred ninety-one thousand, five hundred twenty-one".