21813120 has 192 divisors, whose sum is σ = 86243040. Its totient is φ = 4976640.

The previous prime is 21813101. The next prime is 21813163. The reversal of 21813120 is 2131812.

It is a tau number, because it is divible by the number of its divisors (192).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21813093 and 21813102.

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 23 ways as a sum of consecutive naturals, for example, 40050 + ... + 40590.

Almost surely, 2^21813120 is an apocalyptic number.

21813120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21813120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43121520).

21813120 is an abundant number, since it is smaller than the sum of its proper divisors (64429920).

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

21813120 is a wasteful number, since it uses less digits than its factorization.

21813120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573 (or 558 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21813120 is about 4670.4517982739. The cubic root of 21813120 is about 279.4082741924.

Adding to 21813120 its reverse (2131812), we get a palindrome (23944932).

The spelling of 21813120 in words is "twenty-one million, eight hundred thirteen thousand, one hundred twenty".