21856297 has 4 divisors (see below), whose sum is σ = 21908880. Its totient is φ = 21803716.

The previous prime is 21856277. The next prime is 21856337. The reversal of 21856297 is 79265812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21856297 - 2¹⁹ = 21332009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21856207) 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, 25663 + ... + 26500.

It is an arithmetic number, because the mean of its divisors is an integer number (5477220).

Almost surely, 2^21856297 is an apocalyptic number.

It is an amenable number.

21856297 is a deficient number, since it is larger than the sum of its proper divisors (52583).

21856297 is an equidigital number, since it uses as much as digits as its factorization.

21856297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52582.

The product of its digits is 60480, while the sum is 40.

The square root of 21856297 is about 4675.0718711053. The cubic root of 21856297 is about 279.5925067391.

The spelling of 21856297 in words is "twenty-one million, eight hundred fifty-six thousand, two hundred ninety-seven".