27978821 has 8 divisors (see below), whose sum is σ = 31903704. Its totient is φ = 24307200.

The previous prime is 27978793. The next prime is 27978827. The reversal of 27978821 is 12887972.

It can be written as a sum of positive squares in 4 ways, for example, as 10797796 + 17181025 = 3286^2 + 4145^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 27978821 - 2¹⁰ = 27977797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27978827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63080 + ... + 63521.

It is an arithmetic number, because the mean of its divisors is an integer number (3987963).

Almost surely, 2^27978821 is an apocalyptic number.

It is an amenable number.

27978821 is a deficient number, since it is larger than the sum of its proper divisors (3924883).

27978821 is a wasteful number, since it uses less digits than its factorization.

27978821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126631.

The product of its digits is 112896, while the sum is 44.

The square root of 27978821 is about 5289.5010161640. The cubic root of 27978821 is about 303.5823160689.

The spelling of 27978821 in words is "twenty-seven million, nine hundred seventy-eight thousand, eight hundred twenty-one".