21079869 has 4 divisors (see below), whose sum is σ = 28106496. Its totient is φ = 14053244.

The previous prime is 21079867. The next prime is 21079879. The reversal of 21079869 is 96897012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21079869 - 2¹ = 21079867 is a prime.

It is a super-2 number, since 2×21079869² = 888721754114322, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21079869.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21079867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3513309 + ... + 3513314.

It is an arithmetic number, because the mean of its divisors is an integer number (7026624).

Almost surely, 2^21079869 is an apocalyptic number.

It is an amenable number.

21079869 is a deficient number, since it is larger than the sum of its proper divisors (7026627).

21079869 is an equidigital number, since it uses as much as digits as its factorization.

21079869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7026626.

The product of its (nonzero) digits is 54432, while the sum is 42.

The square root of 21079869 is about 4591.2818471534. The cubic root of 21079869 is about 276.2417410497.

The spelling of 21079869 in words is "twenty-one million, seventy-nine thousand, eight hundred sixty-nine".