27990921 has 16 divisors (see below), whose sum is σ = 42747264. Its totient is φ = 15959424.

The previous prime is 27990917. The next prime is 27990929. The reversal of 27990921 is 12909972.

It is a happy number.

27990921 is nontrivially palindromic in base 12.

It is not a de Polignac number, because 27990921 - 2² = 27990917 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 27990921.

It is not an unprimeable number, because it can be changed into a prime (27990929) 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 15 ways as a sum of consecutive naturals, for example, 10501 + ... + 12893.

It is an arithmetic number, because the mean of its divisors is an integer number (2671704).

Almost surely, 2^27990921 is an apocalyptic number.

27990921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

27990921 is a deficient number, since it is larger than the sum of its proper divisors (14756343).

27990921 is a wasteful number, since it uses less digits than its factorization.

27990921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2960.

The product of its (nonzero) digits is 20412, while the sum is 39.

The square root of 27990921 is about 5290.6446677130. The cubic root of 27990921 is about 303.6260731738.

The spelling of 27990921 in words is "twenty-seven million, nine hundred ninety thousand, nine hundred twenty-one".