21424871 has 4 divisors (see below), whose sum is σ = 23072952. Its totient is φ = 19776792.

The previous prime is 21424861. The next prime is 21424877. The reversal of 21424871 is 17842412.

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 21424871 - 2¹⁸ = 21162727 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 (21424877) 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, 824021 + ... + 824046.

It is an arithmetic number, because the mean of its divisors is an integer number (5768238).

Almost surely, 2^21424871 is an apocalyptic number.

21424871 is a deficient number, since it is larger than the sum of its proper divisors (1648081).

21424871 is a wasteful number, since it uses less digits than its factorization.

21424871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1648080.

The product of its digits is 3584, while the sum is 29.

The square root of 21424871 is about 4628.7007896385. The cubic root of 21424871 is about 277.7406229357.

The spelling of 21424871 in words is "twenty-one million, four hundred twenty-four thousand, eight hundred seventy-one".