21864297 has 24 divisors (see below), whose sum is σ = 36007104. Its totient is φ = 11492064.

The previous prime is 21864287. The next prime is 21864301. The reversal of 21864297 is 79246812.

It is not a de Polignac number, because 21864297 - 2⁴ = 21864281 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21864217) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 77118 + ... + 77400.

It is an arithmetic number, because the mean of its divisors is an integer number (1500296).

Almost surely, 2^21864297 is an apocalyptic number.

It is an amenable number.

21864297 is a deficient number, since it is larger than the sum of its proper divisors (14142807).

21864297 is an equidigital number, since it uses as much as digits as its factorization.

21864297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 589 (or 306 counting only the distinct ones).

The product of its digits is 48384, while the sum is 39.

The square root of 21864297 is about 4675.9273946459. The cubic root of 21864297 is about 279.6266154021.

The spelling of 21864297 in words is "twenty-one million, eight hundred sixty-four thousand, two hundred ninety-seven".