15981281 has 2 divisors, whose sum is σ = 15981282. Its totient is φ = 15981280.

The previous prime is 15981263. The next prime is 15981283. The reversal of 15981281 is 18218951.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10144225 + 5837056 = 3185^2 + 2416^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15981281 is a prime.

It is a super-2 number, since 2×15981281² = 510802684801922, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 15981283, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (15981283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7990640 + 7990641.

It is an arithmetic number, because the mean of its divisors is an integer number (7990641).

Almost surely, 2^15981281 is an apocalyptic number.

It is an amenable number.

15981281 is a deficient number, since it is larger than the sum of its proper divisors (1).

15981281 is an equidigital number, since it uses as much as digits as its factorization.

15981281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 35.

The square root of 15981281 is about 3997.6594402225. The cubic root of 15981281 is about 251.8859030391.

Subtracting 15981281 from its reverse (18218951), we obtain a triangular number (2237670 = T₂₁₁₅).

The spelling of 15981281 in words is "fifteen million, nine hundred eighty-one thousand, two hundred eighty-one".