21291120 has 80 divisors (see below), whose sum is σ = 73343520. Its totient is φ = 5677056.

The previous prime is 21291119. The next prime is 21291139. The reversal of 21291120 is 2119212.

It is a tau number, because it is divible by the number of its divisors (80).

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 = 21291093 and 21291102.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2769 + ... + 7088.

It is an arithmetic number, because the mean of its divisors is an integer number (916794).

Almost surely, 2^21291120 is an apocalyptic number.

21291120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21291120 is an abundant number, since it is smaller than the sum of its proper divisors (52052400).

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

21291120 is a wasteful number, since it uses less digits than its factorization.

21291120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9879 (or 9867 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21291120 is about 4614.2301633100. The cubic root of 21291120 is about 277.1614571324.

It can be divided in two parts, 2129 and 1120, that added together give a square (3249 = 57²).

The spelling of 21291120 in words is "twenty-one million, two hundred ninety-one thousand, one hundred twenty".