27931021 has 2 divisors, whose sum is σ = 27931022. Its totient is φ = 27931020.

The previous prime is 27931009. The next prime is 27931049. The reversal of 27931021 is 12013972.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22705225 + 5225796 = 4765^2 + 2286^2 .

It is a cyclic number.

It is not a de Polignac number, because 27931021 - 2¹⁵ = 27898253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27931061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13965510 + 13965511.

It is an arithmetic number, because the mean of its divisors is an integer number (13965511).

Almost surely, 2^27931021 is an apocalyptic number.

It is an amenable number.

27931021 is a deficient number, since it is larger than the sum of its proper divisors (1).

27931021 is an equidigital number, since it uses as much as digits as its factorization.

27931021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 27931021 is about 5284.9807000594. The cubic root of 27931021 is about 303.4093339599.

Adding to 27931021 its reverse (12013972), we get a palindrome (39944993).

The spelling of 27931021 in words is "twenty-seven million, nine hundred thirty-one thousand, twenty-one".