21755743 has 4 divisors (see below), whose sum is σ = 21817728. Its totient is φ = 21693760.

The previous prime is 21755717. The next prime is 21755761. The reversal of 21755743 is 34755712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21755743 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21755699 and 21755708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21755143) 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, 30463 + ... + 31168.

It is an arithmetic number, because the mean of its divisors is an integer number (5454432).

Almost surely, 2^21755743 is an apocalyptic number.

21755743 is a deficient number, since it is larger than the sum of its proper divisors (61985).

21755743 is an equidigital number, since it uses as much as digits as its factorization.

21755743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61984.

The product of its digits is 29400, while the sum is 34.

The square root of 21755743 is about 4664.3052001343. The cubic root of 21755743 is about 279.1630748876.

The spelling of 21755743 in words is "twenty-one million, seven hundred fifty-five thousand, seven hundred forty-three".