21840516 has 30 divisors (see below), whose sum is σ = 57096270. Its totient is φ = 7280064.

The previous prime is 21840499. The next prime is 21840521. The reversal of 21840516 is 61504812.

It can be written as a sum of positive squares in only one way, i.e., 19766916 + 2073600 = 4446^2 + 1440^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21840516.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 33381 + ... + 34028.

It is an arithmetic number, because the mean of its divisors is an integer number (1903209).

Almost surely, 2^21840516 is an apocalyptic number.

It is an amenable number.

21840516 is an abundant number, since it is smaller than the sum of its proper divisors (35255754).

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

21840516 is a wasteful number, since it uses less digits than its factorization.

21840516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67425 (or 67414 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21840516 is about 4673.3837847966. The cubic root of 21840516 is about 279.5251987270.

The spelling of 21840516 in words is "twenty-one million, eight hundred forty thousand, five hundred sixteen".