27815877721 has 2 divisors, whose sum is σ = 27815877722. Its totient is φ = 27815877720.

The previous prime is 27815877703. The next prime is 27815877737. The reversal of 27815877721 is 12777851872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20239045696 + 7576832025 = 142264^2 + 87045^2 .

It is a cyclic number.

It is not a de Polignac number, because 27815877721 - 2⁹ = 27815877209 is a prime.

It is not a weakly prime, because it can be changed into another prime (27815877781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13907938860 + 13907938861.

It is an arithmetic number, because the mean of its divisors is an integer number (13907938861).

Almost surely, 2^27815877721 is an apocalyptic number.

It is an amenable number.

27815877721 is a deficient number, since it is larger than the sum of its proper divisors (1).

27815877721 is an equidigital number, since it uses as much as digits as its factorization.

27815877721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3073280, while the sum is 55.

The spelling of 27815877721 in words is "twenty-seven billion, eight hundred fifteen million, eight hundred seventy-seven thousand, seven hundred twenty-one".