21879081 has 12 divisors (see below), whose sum is σ = 36117952. Its totient is φ = 12502296.

The previous prime is 21879047. The next prime is 21879083. The reversal of 21879081 is 18097812.

It is not a de Polignac number, because 21879081 - 2⁹ = 21878569 is a prime.

It is a super-2 number, since 2×21879081² = 957388370809122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21879083) 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 11 ways as a sum of consecutive naturals, for example, 173581 + ... + 173706.

Almost surely, 2^21879081 is an apocalyptic number.

21879081 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21879081 is a deficient number, since it is larger than the sum of its proper divisors (14238871).

21879081 is a wasteful number, since it uses less digits than its factorization.

21879081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347300 (or 347297 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 21879081 is about 4677.5079903727. The cubic root of 21879081 is about 279.6896263230.

The spelling of 21879081 in words is "twenty-one million, eight hundred seventy-nine thousand, eighty-one".