21161827 has 4 divisors (see below), whose sum is σ = 21173296. Its totient is φ = 21150360.

The previous prime is 21161783. The next prime is 21161857. The reversal of 21161827 is 72816112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21161827 - 2¹¹ = 21159779 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21161795 and 21161804.

It is not an unprimeable number, because it can be changed into a prime (21161857) 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 3 ways as a sum of consecutive naturals, for example, 2268 + ... + 6889.

It is an arithmetic number, because the mean of its divisors is an integer number (5293324).

Almost surely, 2^21161827 is an apocalyptic number.

21161827 is a deficient number, since it is larger than the sum of its proper divisors (11469).

21161827 is an equidigital number, since it uses as much as digits as its factorization.

21161827 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11468.

The product of its digits is 1344, while the sum is 28.

The square root of 21161827 is about 4600.1985826701. The cubic root of 21161827 is about 276.5992850536.

Adding to 21161827 its reverse (72816112), we get a palindrome (93977939).

The spelling of 21161827 in words is "twenty-one million, one hundred sixty-one thousand, eight hundred twenty-seven".