21091814 has 16 divisors (see below), whose sum is σ = 32522688. Its totient is φ = 10253952.

The previous prime is 21091793. The next prime is 21091823. The reversal of 21091814 is 41819012.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 15614 + ... + 16910.

It is an arithmetic number, because the mean of its divisors is an integer number (2032668).

Almost surely, 2^21091814 is an apocalyptic number.

21091814 is a deficient number, since it is larger than the sum of its proper divisors (11430874).

21091814 is a wasteful number, since it uses less digits than its factorization.

21091814 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1519.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 21091814 is about 4592.5824978981. The cubic root of 21091814 is about 276.2939090609.

The spelling of 21091814 in words is "twenty-one million, ninety-one thousand, eight hundred fourteen".