21424191 has 16 divisors (see below), whose sum is σ = 30771840. Its totient is φ = 13214880.

The previous prime is 21424189. The next prime is 21424213. The reversal of 21424191 is 19142412.

21424191 = 456² + 457² + ... + 541².

It is not a de Polignac number, because 21424191 - 2¹ = 21424189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424171) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1920 + ... + 6821.

It is an arithmetic number, because the mean of its divisors is an integer number (1923240).

Almost surely, 2^21424191 is an apocalyptic number.

21424191 is a deficient number, since it is larger than the sum of its proper divisors (9347649).

21424191 is a wasteful number, since it uses less digits than its factorization.

21424191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8806.

The product of its digits is 576, while the sum is 24.

The square root of 21424191 is about 4628.6273343185. The cubic root of 21424191 is about 277.7376845186.

The spelling of 21424191 in words is "twenty-one million, four hundred twenty-four thousand, one hundred ninety-one".