21111879 has 8 divisors (see below), whose sum is σ = 28176880. Its totient is φ = 14060736.

The previous prime is 21111877. The next prime is 21111931. The reversal of 21111879 is 97811112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21111879 - 2¹ = 21111877 is a prime.

It is a super-2 number, since 2×21111879² = 891422869821282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111877) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 867 + ... + 6555.

It is an arithmetic number, because the mean of its divisors is an integer number (3522110).

Almost surely, 2^21111879 is an apocalyptic number.

21111879 is a deficient number, since it is larger than the sum of its proper divisors (7065001).

21111879 is a wasteful number, since it uses less digits than its factorization.

21111879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6929.

The product of its digits is 1008, while the sum is 30.

The square root of 21111879 is about 4594.7664793763. The cubic root of 21111879 is about 276.3814956515.

It can be divided in two parts, 211 and 11879, that added together give a triangular number (12090 = T₁₅₅).

The spelling of 21111879 in words is "twenty-one million, one hundred eleven thousand, eight hundred seventy-nine".