21855671 has 2 divisors, whose sum is σ = 21855672. Its totient is φ = 21855670.

The previous prime is 21855649. The next prime is 21855679. The reversal of 21855671 is 17655812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21855671 - 2⁶ = 21855607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21855679) 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, 10927835 + 10927836.

It is an arithmetic number, because the mean of its divisors is an integer number (10927836).

Almost surely, 2^21855671 is an apocalyptic number.

21855671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21855671 is an equidigital number, since it uses as much as digits as its factorization.

21855671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16800, while the sum is 35.

The square root of 21855671 is about 4675.0049197835. The cubic root of 21855671 is about 279.5898373851.

The spelling of 21855671 in words is "twenty-one million, eight hundred fifty-five thousand, six hundred seventy-one".