21767121 has 12 divisors (see below), whose sum is σ = 31603572. Its totient is φ = 14436576.

The previous prime is 21767099. The next prime is 21767147. The reversal of 21767121 is 12176712.

It can be written as a sum of positive squares in 2 ways, for example, as 12531600 + 9235521 = 3540^2 + 3039^2 .

It is not a de Polignac number, because 21767121 - 2¹⁰ = 21766097 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21767171) 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 11 ways as a sum of consecutive naturals, for example, 4366 + ... + 7911.

It is an arithmetic number, because the mean of its divisors is an integer number (2633631).

Almost surely, 2^21767121 is an apocalyptic number.

It is an amenable number.

21767121 is a deficient number, since it is larger than the sum of its proper divisors (9836451).

21767121 is a wasteful number, since it uses less digits than its factorization.

21767121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12480 (or 12477 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 21767121 is about 4665.5247293311. The cubic root of 21767121 is about 279.2117327508.

The spelling of 21767121 in words is "twenty-one million, seven hundred sixty-seven thousand, one hundred twenty-one".