21852720 has 160 divisors (see below), whose sum is σ = 76899840. Its totient is φ = 5702400.

The previous prime is 21852683. The next prime is 21852749. The reversal of 21852720 is 2725812.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 31 ways as a sum of consecutive naturals, for example, 144645 + ... + 144795.

It is an arithmetic number, because the mean of its divisors is an integer number (480624).

Almost surely, 2^21852720 is an apocalyptic number.

21852720 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 21852720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38449920).

21852720 is an abundant number, since it is smaller than the sum of its proper divisors (55047120).

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

21852720 is a wasteful number, since it uses less digits than its factorization.

21852720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240 (or 228 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21852720 is about 4674.6892944879. The cubic root of 21852720 is about 279.5772532104.

It can be divided in two parts, 21 and 852720, that multiplied together give a triangular number (17907120 = T₅₉₈₄).

The spelling of 21852720 in words is "twenty-one million, eight hundred fifty-two thousand, seven hundred twenty".