21571879 has 4 divisors (see below), whose sum is σ = 24653584. Its totient is φ = 18490176.

The previous prime is 21571867. The next prime is 21571903. The reversal of 21571879 is 97817512.

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 21571879 - 2⁹ = 21571367 is a prime.

It is a Duffinian number.

It is a plaindrome in base 8.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21571279) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1540842 + ... + 1540855.

It is an arithmetic number, because the mean of its divisors is an integer number (6163396).

Almost surely, 2^21571879 is an apocalyptic number.

21571879 is a deficient number, since it is larger than the sum of its proper divisors (3081705).

21571879 is an equidigital number, since it uses as much as digits as its factorization.

21571879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3081704.

The product of its digits is 35280, while the sum is 40.

The square root of 21571879 is about 4644.5536922292. The cubic root of 21571879 is about 278.3744200126.

The spelling of 21571879 in words is "twenty-one million, five hundred seventy-one thousand, eight hundred seventy-nine".