27971991 has 12 divisors (see below), whose sum is σ = 40477320. Its totient is φ = 18614160.

The previous prime is 27971989. The next prime is 27972023. The reversal of 27971991 is 19917972.

It is not a de Polignac number, because 27971991 - 2¹ = 27971989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27971291) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3061 + ... + 8081.

It is an arithmetic number, because the mean of its divisors is an integer number (3373110).

Almost surely, 2^27971991 is an apocalyptic number.

27971991 is a deficient number, since it is larger than the sum of its proper divisors (12505329).

27971991 is a wasteful number, since it uses less digits than its factorization.

27971991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5646 (or 5643 counting only the distinct ones).

The product of its digits is 71442, while the sum is 45.

The square root of 27971991 is about 5288.8553582037. The cubic root of 27971991 is about 303.5576112399.

The spelling of 27971991 in words is "twenty-seven million, nine hundred seventy-one thousand, nine hundred ninety-one".