21181842 has 24 divisors (see below), whose sum is σ = 50066640. Its totient is φ = 6418680.

The previous prime is 21181837. The next prime is 21181877. The reversal of 21181842 is 24818112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 53292 + ... + 53687.

It is an arithmetic number, because the mean of its divisors is an integer number (2086110).

Almost surely, 2^21181842 is an apocalyptic number.

21181842 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21181842 is an abundant number, since it is smaller than the sum of its proper divisors (28884798).

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

21181842 is a wasteful number, since it uses less digits than its factorization.

21181842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106998 (or 106995 counting only the distinct ones).

The product of its digits is 1024, while the sum is 27.

The square root of 21181842 is about 4602.3735180882. The cubic root of 21181842 is about 276.6864607376.

Adding to 21181842 its reverse (24818112), we get a palindrome (45999954).

The spelling of 21181842 in words is "twenty-one million, one hundred eighty-one thousand, eight hundred forty-two".