27991945 has 8 divisors (see below), whose sum is σ = 35566344. Its totient is φ = 21076224.

The previous prime is 27991939. The next prime is 27991967. The reversal of 27991945 is 54919972.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1149184 + 26842761 = 1072^2 + 5181^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-27991945 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 27991895 and 27991904.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164574 + ... + 164743.

It is an arithmetic number, because the mean of its divisors is an integer number (4445793).

Almost surely, 2^27991945 is an apocalyptic number.

It is an amenable number.

27991945 is a deficient number, since it is larger than the sum of its proper divisors (7574399).

27991945 is a wasteful number, since it uses less digits than its factorization.

27991945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329339.

The product of its digits is 204120, while the sum is 46.

The square root of 27991945 is about 5290.7414414239. The cubic root of 27991945 is about 303.6297756756.

The spelling of 27991945 in words is "twenty-seven million, nine hundred ninety-one thousand, nine hundred forty-five".