21023447 has 4 divisors (see below), whose sum is σ = 21536256. Its totient is φ = 20510640.

The previous prime is 21023419. The next prime is 21023459. The reversal of 21023447 is 74432012.

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 21023447 - 2⁶ = 21023383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023417) 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, 256343 + ... + 256424.

It is an arithmetic number, because the mean of its divisors is an integer number (5384064).

Almost surely, 2^21023447 is an apocalyptic number.

21023447 is a deficient number, since it is larger than the sum of its proper divisors (512809).

21023447 is an equidigital number, since it uses as much as digits as its factorization.

21023447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512808.

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 21023447 is about 4585.1332586960. The cubic root of 21023447 is about 275.9950595979.

Adding to 21023447 its reverse (74432012), we get a palindrome (95455459).

The spelling of 21023447 in words is "twenty-one million, twenty-three thousand, four hundred forty-seven".