13821581 has 2 divisors, whose sum is σ = 13821582. Its totient is φ = 13821580.

The previous prime is 13821571. The next prime is 13821583. The reversal of 13821581 is 18512831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11115556 + 2706025 = 3334^2 + 1645^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13821581 is a prime.

It is a super-2 number, since 2×13821581² = 382072202679122, which contains 22 as substring.

Together with 13821583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13821583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6910790 + 6910791.

It is an arithmetic number, because the mean of its divisors is an integer number (6910791).

Almost surely, 2^13821581 is an apocalyptic number.

It is an amenable number.

13821581 is a deficient number, since it is larger than the sum of its proper divisors (1).

13821581 is an equidigital number, since it uses as much as digits as its factorization.

13821581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1920, while the sum is 29.

The square root of 13821581 is about 3717.7386944217. The cubic root of 13821581 is about 239.9860003408.

The spelling of 13821581 in words is "thirteen million, eight hundred twenty-one thousand, five hundred eighty-one".