21423760 has 20 divisors (see below), whose sum is σ = 49810428. Its totient is φ = 8569472.

The previous prime is 21423751. The next prime is 21423763. The reversal of 21423760 is 6732412.

It can be written as a sum of positive squares in 2 ways, for example, as 5837056 + 15586704 = 2416^2 + 3948^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (21423763) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 133819 + ... + 133978.

Almost surely, 2^21423760 is an apocalyptic number.

21423760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21423760 is an abundant number, since it is smaller than the sum of its proper divisors (28386668).

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

21423760 is a wasteful number, since it uses less digits than its factorization.

21423760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267810 (or 267804 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 21423760 is about 4628.5807760047. The cubic root of 21423760 is about 277.7358220485.

The spelling of 21423760 in words is "twenty-one million, four hundred twenty-three thousand, seven hundred sixty".