21424743 has 20 divisors (see below), whose sum is σ = 33889680. Its totient is φ = 13442112.

The previous prime is 21424699. The next prime is 21424759. The reversal of 21424743 is 34742412.

It is not a de Polignac number, because 21424743 - 2⁶ = 21424679 is a prime.

It is a super-2 number, since 2×21424743² = 918039225232098, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424763) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6403 + ... + 9156.

It is an arithmetic number, because the mean of its divisors is an integer number (1694484).

Almost surely, 2^21424743 is an apocalyptic number.

21424743 is a deficient number, since it is larger than the sum of its proper divisors (12464937).

21424743 is a wasteful number, since it uses less digits than its factorization.

21424743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15588 (or 15579 counting only the distinct ones).

The product of its digits is 5376, while the sum is 27.

The square root of 21424743 is about 4628.6869628438. The cubic root of 21424743 is about 277.7400698266.

The spelling of 21424743 in words is "twenty-one million, four hundred twenty-four thousand, seven hundred forty-three".