27781009 has 4 divisors (see below), whose sum is σ = 29415204. Its totient is φ = 26146816.

The previous prime is 27781003. The next prime is 27781027. The reversal of 27781009 is 90018772.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 23668225 + 4112784 = 4865^2 + 2028^2 .

It is not a de Polignac number, because 27781009 - 2³ = 27781001 is a prime.

It is a super-2 number, since 2×27781009² = 1543568922116162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27781001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 817072 + ... + 817105.

It is an arithmetic number, because the mean of its divisors is an integer number (7353801).

Almost surely, 2^27781009 is an apocalyptic number.

It is an amenable number.

27781009 is a deficient number, since it is larger than the sum of its proper divisors (1634195).

27781009 is a wasteful number, since it uses less digits than its factorization.

27781009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1634194.

The product of its (nonzero) digits is 7056, while the sum is 34.

The square root of 27781009 is about 5270.7692986888. The cubic root of 27781009 is about 302.8651747243.

The spelling of 27781009 in words is "twenty-seven million, seven hundred eighty-one thousand, nine".