21894643 has 4 divisors (see below), whose sum is σ = 22846608. Its totient is φ = 20942680.

The previous prime is 21894641. The next prime is 21894647. The reversal of 21894643 is 34649812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21894643 - 2¹ = 21894641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21894641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 475948 + ... + 475993.

It is an arithmetic number, because the mean of its divisors is an integer number (5711652).

Almost surely, 2^21894643 is an apocalyptic number.

21894643 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21894643 is a deficient number, since it is larger than the sum of its proper divisors (951965).

21894643 is an equidigital number, since it uses as much as digits as its factorization.

21894643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 951964.

The product of its digits is 41472, while the sum is 37.

The square root of 21894643 is about 4679.1711872937. The cubic root of 21894643 is about 279.7559225022.

The spelling of 21894643 in words is "twenty-one million, eight hundred ninety-four thousand, six hundred forty-three".