13581781 has 2 divisors, whose sum is σ = 13581782. Its totient is φ = 13581780.

The previous prime is 13581749. The next prime is 13581811. The reversal of 13581781 is 18718531.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13256881 + 324900 = 3641^2 + 570^2 .

It is a cyclic number.

It is not a de Polignac number, because 13581781 - 2⁵ = 13581749 is a prime.

It is a super-2 number, since 2×13581781² = 368929550263922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13581481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6790890 + 6790891.

It is an arithmetic number, because the mean of its divisors is an integer number (6790891).

Almost surely, 2^13581781 is an apocalyptic number.

It is an amenable number.

13581781 is a deficient number, since it is larger than the sum of its proper divisors (1).

13581781 is an equidigital number, since it uses as much as digits as its factorization.

13581781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 34.

The square root of 13581781 is about 3685.3467950791. The cubic root of 13581781 is about 238.5900021737.

The spelling of 13581781 in words is "thirteen million, five hundred eighty-one thousand, seven hundred eighty-one".