21854591 has 4 divisors (see below), whose sum is σ = 23841384. Its totient is φ = 19867800.

The previous prime is 21854587. The next prime is 21854593. The reversal of 21854591 is 19545812.

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 21854591 - 2² = 21854587 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21854593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 993380 + ... + 993401.

It is an arithmetic number, because the mean of its divisors is an integer number (5960346).

Almost surely, 2^21854591 is an apocalyptic number.

21854591 is a deficient number, since it is larger than the sum of its proper divisors (1986793).

21854591 is a wasteful number, since it uses less digits than its factorization.

21854591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1986792.

The product of its digits is 14400, while the sum is 35.

The square root of 21854591 is about 4674.8894104567. The cubic root of 21854591 is about 279.5852319900.

It can be divided in two parts, 2185 and 4591, that added together give a palindrome (6776).

The spelling of 21854591 in words is "twenty-one million, eight hundred fifty-four thousand, five hundred ninety-one".