21945743 has 4 divisors (see below), whose sum is σ = 21973680. Its totient is φ = 21917808.

The previous prime is 21945689. The next prime is 21945751. The reversal of 21945743 is 34754912.

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 21945743 - 2²² = 17751439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945043) 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, 12755 + ... + 14372.

It is an arithmetic number, because the mean of its divisors is an integer number (5493420).

Almost surely, 2^21945743 is an apocalyptic number.

21945743 is a deficient number, since it is larger than the sum of its proper divisors (27937).

21945743 is an equidigital number, since it uses as much as digits as its factorization.

21945743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27936.

The product of its digits is 30240, while the sum is 35.

The square root of 21945743 is about 4684.6283737347. The cubic root of 21945743 is about 279.9733945809.

The spelling of 21945743 in words is "twenty-one million, nine hundred forty-five thousand, seven hundred forty-three".