21997743 has 4 divisors (see below), whose sum is σ = 29330328. Its totient is φ = 14665160.

The previous prime is 21997733. The next prime is 21997751. The reversal of 21997743 is 34779912.

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 21997743 - 2⁸ = 21997487 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21997695 and 21997704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21997733) 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, 3666288 + ... + 3666293.

It is an arithmetic number, because the mean of its divisors is an integer number (7332582).

Almost surely, 2^21997743 is an apocalyptic number.

21997743 is a deficient number, since it is larger than the sum of its proper divisors (7332585).

21997743 is an equidigital number, since it uses as much as digits as its factorization.

21997743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7332584.

The product of its digits is 95256, while the sum is 42.

The square root of 21997743 is about 4690.1751566439. The cubic root of 21997743 is about 280.1943506124.

The spelling of 21997743 in words is "twenty-one million, nine hundred ninety-seven thousand, seven hundred forty-three".