21236743 has 8 divisors (see below), whose sum is σ = 23256720. Its totient is φ = 19231680.

The previous prime is 21236731. The next prime is 21236749. The reversal of 21236743 is 34763212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21236743 - 2¹⁷ = 21105671 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21236749) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 630 + ... + 6547.

It is an arithmetic number, because the mean of its divisors is an integer number (2907090).

Almost surely, 2^21236743 is an apocalyptic number.

21236743 is a deficient number, since it is larger than the sum of its proper divisors (2019977).

21236743 is a wasteful number, since it uses less digits than its factorization.

21236743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7457.

The product of its digits is 6048, while the sum is 28.

The square root of 21236743 is about 4608.3340807715. The cubic root of 21236743 is about 276.9253014442.

Adding to 21236743 its reverse (34763212), we get a palindrome (55999955).

The spelling of 21236743 in words is "twenty-one million, two hundred thirty-six thousand, seven hundred forty-three".