21854819 has 4 divisors (see below), whose sum is σ = 24976944. Its totient is φ = 18732696.

The previous prime is 21854803. The next prime is 21854837. The reversal of 21854819 is 91845812.

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 21854819 - 2⁴ = 21854803 is a prime.

It is a super-3 number, since 3×21854819³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21854869) 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, 1561052 + ... + 1561065.

It is an arithmetic number, because the mean of its divisors is an integer number (6244236).

Almost surely, 2^21854819 is an apocalyptic number.

21854819 is a deficient number, since it is larger than the sum of its proper divisors (3122125).

21854819 is an equidigital number, since it uses as much as digits as its factorization.

21854819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3122124.

The product of its digits is 23040, while the sum is 38.

The square root of 21854819 is about 4674.9137959967. The cubic root of 21854819 is about 279.5862042527.

The spelling of 21854819 in words is "twenty-one million, eight hundred fifty-four thousand, eight hundred nineteen".