27781993 has 2 divisors, whose sum is σ = 27781994. Its totient is φ = 27781992.

The previous prime is 27781987. The next prime is 27782003. The reversal of 27781993 is 39918772.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22250089 + 5531904 = 4717^2 + 2352^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27781993 is a prime.

It is not a weakly prime, because it can be changed into another prime (27781903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13890996 + 13890997.

It is an arithmetic number, because the mean of its divisors is an integer number (13890997).

Almost surely, 2^27781993 is an apocalyptic number.

It is an amenable number.

27781993 is a deficient number, since it is larger than the sum of its proper divisors (1).

27781993 is an equidigital number, since it uses as much as digits as its factorization.

27781993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 190512, while the sum is 46.

The square root of 27781993 is about 5270.8626428698. The cubic root of 27781993 is about 302.8687504981.

The spelling of 27781993 in words is "twenty-seven million, seven hundred eighty-one thousand, nine hundred ninety-three".