21634823 has 6 divisors (see below), whose sum is σ = 25167096. Its totient is φ = 18544092.

The previous prime is 21634813. The next prime is 21634849. The reversal of 21634823 is 32843612.

It is not a de Polignac number, because 21634823 - 2¹² = 21630727 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 (21634813) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 220715 + ... + 220812.

It is an arithmetic number, because the mean of its divisors is an integer number (4194516).

Almost surely, 2^21634823 is an apocalyptic number.

21634823 is a deficient number, since it is larger than the sum of its proper divisors (3532273).

21634823 is an equidigital number, since it uses as much as digits as its factorization.

21634823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441541 (or 441534 counting only the distinct ones).

The product of its digits is 6912, while the sum is 29.

The square root of 21634823 is about 4651.3248650250. The cubic root of 21634823 is about 278.6449108175.

The spelling of 21634823 in words is "twenty-one million, six hundred thirty-four thousand, eight hundred twenty-three".