27977981 has 2 divisors, whose sum is σ = 27977982. Its totient is φ = 27977980.

The previous prime is 27977923. The next prime is 27978017. The reversal of 27977981 is 18977972.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23609881 + 4368100 = 4859^2 + 2090^2 .

It is a cyclic number.

It is not a de Polignac number, because 27977981 - 2²² = 23783677 is a prime.

It is a super-2 number, since 2×27977981² = 1565534841672722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27977281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13988990 + 13988991.

It is an arithmetic number, because the mean of its divisors is an integer number (13988991).

Almost surely, 2^27977981 is an apocalyptic number.

It is an amenable number.

27977981 is a deficient number, since it is larger than the sum of its proper divisors (1).

27977981 is an equidigital number, since it uses as much as digits as its factorization.

27977981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 444528, while the sum is 50.

The square root of 27977981 is about 5289.4216129932. The cubic root of 27977981 is about 303.5792779173.

Subtracting from 27977981 its reverse (18977972), we obtain a palindrome (9000009).

The spelling of 27977981 in words is "twenty-seven million, nine hundred seventy-seven thousand, nine hundred eighty-one".