27949821857 has 2 divisors, whose sum is σ = 27949821858. Its totient is φ = 27949821856.

The previous prime is 27949821841. The next prime is 27949821899. The reversal of 27949821857 is 75812894972.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22790129296 + 5159692561 = 150964^2 + 71831^2 .

It is a cyclic number.

It is not a de Polignac number, because 27949821857 - 2⁴ = 27949821841 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 27949821857.

It is not a weakly prime, because it can be changed into another prime (27949821157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13974910928 + 13974910929.

It is an arithmetic number, because the mean of its divisors is an integer number (13974910929).

Almost surely, 2^27949821857 is an apocalyptic number.

It is an amenable number.

27949821857 is a deficient number, since it is larger than the sum of its proper divisors (1).

27949821857 is an equidigital number, since it uses as much as digits as its factorization.

27949821857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20321280, while the sum is 62.

The spelling of 27949821857 in words is "twenty-seven billion, nine hundred forty-nine million, eight hundred twenty-one thousand, eight hundred fifty-seven".