21115827 has 6 divisors (see below), whose sum is σ = 30500652. Its totient is φ = 14077212.

The previous prime is 21115793. The next prime is 21115837. The reversal of 21115827 is 72851112.

It is not a de Polignac number, because 21115827 - 2¹⁰ = 21114803 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21115827.

It is not an unprimeable number, because it can be changed into a prime (21115837) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1173093 + ... + 1173110.

It is an arithmetic number, because the mean of its divisors is an integer number (5083442).

Almost surely, 2^21115827 is an apocalyptic number.

21115827 is a deficient number, since it is larger than the sum of its proper divisors (9384825).

21115827 is a wasteful number, since it uses less digits than its factorization.

21115827 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2346209 (or 2346206 counting only the distinct ones).

The product of its digits is 1120, while the sum is 27.

The square root of 21115827 is about 4595.1960785150. The cubic root of 21115827 is about 276.3987227007.

Adding to 21115827 its reverse (72851112), we get a palindrome (93966939).

The spelling of 21115827 in words is "twenty-one million, one hundred fifteen thousand, eight hundred twenty-seven".