27991800 has 72 divisors (see below), whose sum is σ = 94011840. Its totient is φ = 7464000.

The previous prime is 27991793. The next prime is 27991801. The reversal of 27991800 is 819972.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

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 polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 5976 + ... + 9575.

It is an arithmetic number, because the mean of its divisors is an integer number (1305720).

Almost surely, 2^27991800 is an apocalyptic number.

27991800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

27991800 is an abundant number, since it is smaller than the sum of its proper divisors (66020040).

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

27991800 is a wasteful number, since it uses less digits than its factorization.

27991800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15573 (or 15561 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 27991800 is about 5290.7277382228. The cubic root of 27991800 is about 303.6292514010.

The spelling of 27991800 in words is "twenty-seven million, nine hundred ninety-one thousand, eight hundred".