21824397 has 40 divisors (see below), whose sum is σ = 37930112. Its totient is φ = 12247200.

The previous prime is 21824381. The next prime is 21824417. The reversal of 21824397 is 79342812.

21824397 is a `hidden beast` number, since 218 + 2 + 439 + 7 = 666.

It is not a de Polignac number, because 21824397 - 2⁴ = 21824381 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21824317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 34272 + ... + 34902.

Almost surely, 2^21824397 is an apocalyptic number.

21824397 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21824397 is a deficient number, since it is larger than the sum of its proper divisors (16105715).

21824397 is an equidigital number, since it uses as much as digits as its factorization.

21824397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711 (or 702 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21824397 is about 4671.6589130629. The cubic root of 21824397 is about 279.4564156211.

The spelling of 21824397 in words is "twenty-one million, eight hundred twenty-four thousand, three hundred ninety-seven".