21440023 has 8 divisors (see below), whose sum is σ = 23481216. Its totient is φ = 19414200.

The previous prime is 21440017. The next prime is 21440039. The reversal of 21440023 is 32004412.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21440023 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21439979 and 21440006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21444023) 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, 813 + ... + 6598.

It is an arithmetic number, because the mean of its divisors is an integer number (2935152).

Almost surely, 2^21440023 is an apocalyptic number.

21440023 is a deficient number, since it is larger than the sum of its proper divisors (2041193).

21440023 is a wasteful number, since it uses less digits than its factorization.

21440023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7685.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21440023 is about 4630.3372447371. The cubic root of 21440023 is about 277.8060816611.

Adding to 21440023 its reverse (32004412), we get a palindrome (53444435).

It can be divided in two parts, 21 and 440023, that added together give a palindrome (440044).

The spelling of 21440023 in words is "twenty-one million, four hundred forty thousand, twenty-three".