27991352861 has 2 divisors, whose sum is σ = 27991352862. Its totient is φ = 27991352860.

The previous prime is 27991352789. The next prime is 27991352869. The reversal of 27991352861 is 16825319972.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27991297636 + 55225 = 167306^2 + 235^2 .

It is a cyclic number.

It is not a de Polignac number, because 27991352861 - 2¹⁸ = 27991090717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27991352869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13995676430 + 13995676431.

It is an arithmetic number, because the mean of its divisors is an integer number (13995676431).

Almost surely, 2^27991352861 is an apocalyptic number.

It is an amenable number.

27991352861 is a deficient number, since it is larger than the sum of its proper divisors (1).

27991352861 is an equidigital number, since it uses as much as digits as its factorization.

27991352861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1632960, while the sum is 53.

The spelling of 27991352861 in words is "twenty-seven billion, nine hundred ninety-one million, three hundred fifty-two thousand, eight hundred sixty-one".