21854687 has 2 divisors, whose sum is σ = 21854688. Its totient is φ = 21854686.

The previous prime is 21854641. The next prime is 21854689. The reversal of 21854687 is 78645812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21854687 - 2⁸ = 21854431 is a prime.

Together with 21854689, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21854689) 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 as a sum of consecutive naturals, namely, 10927343 + 10927344.

It is an arithmetic number, because the mean of its divisors is an integer number (10927344).

Almost surely, 2^21854687 is an apocalyptic number.

21854687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21854687 is an equidigital number, since it uses as much as digits as its factorization.

21854687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 107520, while the sum is 41.

The square root of 21854687 is about 4674.8996780680. The cubic root of 21854687 is about 279.5856413646.

The spelling of 21854687 in words is "twenty-one million, eight hundred fifty-four thousand, six hundred eighty-seven".