21854459 has 4 divisors (see below), whose sum is σ = 23841240. Its totient is φ = 19867680.

The previous prime is 21854431. The next prime is 21854461. The reversal of 21854459 is 95445812.

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 21854459 - 2²⁴ = 5077243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21854419) 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, 993374 + ... + 993395.

It is an arithmetic number, because the mean of its divisors is an integer number (5960310).

Almost surely, 2^21854459 is an apocalyptic number.

21854459 is a deficient number, since it is larger than the sum of its proper divisors (1986781).

21854459 is a wasteful number, since it uses less digits than its factorization.

21854459 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1986780.

The product of its digits is 57600, while the sum is 38.

The square root of 21854459 is about 4674.8752924543. The cubic root of 21854459 is about 279.5846690980.

The spelling of 21854459 in words is "twenty-one million, eight hundred fifty-four thousand, four hundred fifty-nine".