27978665 has 32 divisors (see below), whose sum is σ = 39916800. Its totient is φ = 18558720.

The previous prime is 27978661. The next prime is 27978701. The reversal of 27978665 is 56687972.

It is not a de Polignac number, because 27978665 - 2² = 27978661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (27978661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 77756 + ... + 78114.

It is an arithmetic number, because the mean of its divisors is an integer number (1247400).

Almost surely, 2^27978665 is an apocalyptic number.

It is an amenable number.

27978665 is a deficient number, since it is larger than the sum of its proper divisors (11938135).

27978665 is a wasteful number, since it uses less digits than its factorization.

27978665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497.

The product of its digits is 1270080, while the sum is 50.

The square root of 27978665 is about 5289.4862699510. The cubic root of 27978665 is about 303.5817518453.

The spelling of 27978665 in words is "twenty-seven million, nine hundred seventy-eight thousand, six hundred sixty-five".