27991806 has 8 divisors (see below), whose sum is σ = 55983624. Its totient is φ = 9330600.

The previous prime is 27991801. The next prime is 27991811. The reversal of 27991806 is 60819972.

It is an interprime number because it is at equal distance from previous prime (27991801) and next prime (27991811).

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

27991806 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (27991801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2332645 + ... + 2332656.

It is an arithmetic number, because the mean of its divisors is an integer number (6997953).

Almost surely, 2^27991806 is an apocalyptic number.

27991806 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

27991806 is a wasteful number, since it uses less digits than its factorization.

27991806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4665306.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 27991806 is about 5290.7283052525. The cubic root of 27991806 is about 303.6292730952.

The spelling of 27991806 in words is "twenty-seven million, nine hundred ninety-one thousand, eight hundred six".