21243120 has 40 divisors (see below), whose sum is σ = 65854416. Its totient is φ = 5664768.

The previous prime is 21243077. The next prime is 21243137. The reversal of 21243120 is 2134212.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21243120.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44017 + ... + 44496.

Almost surely, 2^21243120 is an apocalyptic number.

21243120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21243120 is an abundant number, since it is smaller than the sum of its proper divisors (44611296).

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

21243120 is a wasteful number, since it uses less digits than its factorization.

21243120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88529 (or 88523 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21243120 is about 4609.0259274602. The cubic root of 21243120 is about 276.9530171807.

Adding to 21243120 its reverse (2134212), we get a palindrome (23377332).

The spelling of 21243120 in words is "twenty-one million, two hundred forty-three thousand, one hundred twenty".