21912084 has 18 divisors (see below), whose sum is σ = 55388970. Its totient is φ = 7304016.

The previous prime is 21912047. The next prime is 21912097. The reversal of 21912084 is 48021912.

It can be written as a sum of positive squares in only one way, i.e., 11492100 + 10419984 = 3390^2 + 3228^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

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 5 ways as a sum of consecutive naturals, for example, 304299 + ... + 304370.

It is an arithmetic number, because the mean of its divisors is an integer number (3077165).

Almost surely, 2^21912084 is an apocalyptic number.

It is an amenable number.

21912084 is an abundant number, since it is smaller than the sum of its proper divisors (33476886).

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

21912084 is a wasteful number, since it uses less digits than its factorization.

21912084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 608679 (or 608674 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21912084 is about 4681.0345010478. The cubic root of 21912084 is about 279.8301861481.

Adding to 21912084 its reverse (48021912), we get a palindrome (69933996).

The spelling of 21912084 in words is "twenty-one million, nine hundred twelve thousand, eighty-four".