21091041 has 6 divisors (see below), whose sum is σ = 30464850. Its totient is φ = 14060688.

The previous prime is 21091009. The next prime is 21091051. The reversal of 21091041 is 14019012.

It can be written as a sum of positive squares in only one way, i.e., 14861025 + 6230016 = 3855^2 + 2496^2 .

It is not a de Polignac number, because 21091041 - 2⁵ = 21091009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21091051) 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 5 ways as a sum of consecutive naturals, for example, 1171716 + ... + 1171733.

It is an arithmetic number, because the mean of its divisors is an integer number (5077475).

Almost surely, 2^21091041 is an apocalyptic number.

It is an amenable number.

21091041 is a deficient number, since it is larger than the sum of its proper divisors (9373809).

21091041 is a wasteful number, since it uses less digits than its factorization.

21091041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2343455 (or 2343452 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21091041 is about 4592.4983396840. The cubic root of 21091041 is about 276.2905336945.

The spelling of 21091041 in words is "twenty-one million, ninety-one thousand, forty-one".