27978109 has 2 divisors, whose sum is σ = 27978110. Its totient is φ = 27978108.

The previous prime is 27978091. The next prime is 27978121. The reversal of 27978109 is 90187972.

It is a happy number.

Together with previous prime (27978091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27772900 + 205209 = 5270^2 + 453^2 .

It is a cyclic number.

It is not a de Polignac number, because 27978109 - 2⁷ = 27977981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27978149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13989054 + 13989055.

It is an arithmetic number, because the mean of its divisors is an integer number (13989055).

Almost surely, 2^27978109 is an apocalyptic number.

It is an amenable number.

27978109 is a deficient number, since it is larger than the sum of its proper divisors (1).

27978109 is an equidigital number, since it uses as much as digits as its factorization.

27978109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 27978109 is about 5289.4337126010. The cubic root of 27978109 is about 303.5797408777.

The spelling of 27978109 in words is "twenty-seven million, nine hundred seventy-eight thousand, one hundred nine".