21443730 has 64 divisors (see below), whose sum is σ = 64171008. Its totient is φ = 4455360.

The previous prime is 21443729. The next prime is 21443753. The reversal of 21443730 is 3734412.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21443730.

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, 2332 + ... + 6951.

It is an arithmetic number, because the mean of its divisors is an integer number (1002672).

Almost surely, 2^21443730 is an apocalyptic number.

21443730 is an abundant number, since it is smaller than the sum of its proper divisors (42727278).

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

21443730 is a wasteful number, since it uses less digits than its factorization.

21443730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9311.

The product of its (nonzero) digits is 2016, while the sum is 24.

The square root of 21443730 is about 4630.7375222528. The cubic root of 21443730 is about 277.8220917154.

The spelling of 21443730 in words is "twenty-one million, four hundred forty-three thousand, seven hundred thirty".