27991656 has 288 divisors, whose sum is σ = 104569920. Its totient is φ = 6842880.

The previous prime is 27991651. The next prime is 27991661. The reversal of 27991656 is 65619972.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (27991651) and next prime (27991661).

Its product of digits (204120) is a multiple of the sum of its prime divisors (40).

It is not an unprimeable number, because it can be changed into a prime (27991651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1646560 + ... + 1646576.

It is an arithmetic number, because the mean of its divisors is an integer number (363090).

Almost surely, 2^27991656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 27991656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52284960).

27991656 is an abundant number, since it is smaller than the sum of its proper divisors (76578264).

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

27991656 is a wasteful number, since it uses less digits than its factorization.

27991656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67 (or 40 counting only the distinct ones).

The product of its digits is 204120, while the sum is 45.

The square root of 27991656 is about 5290.7141294914. The cubic root of 27991656 is about 303.6287307404.

It can be divided in two parts, 279916 and 56, that added together give a palindrome (279972).

The spelling of 27991656 in words is "twenty-seven million, nine hundred ninety-one thousand, six hundred fifty-six".