21309093 has 12 divisors (see below), whose sum is σ = 33147660. Its totient is φ = 13113216.

The previous prime is 21309061. The next prime is 21309103. The reversal of 21309093 is 39090312.

It can be written as a sum of positive squares in 2 ways, for example, as 4809249 + 16499844 = 2193^2 + 4062^2 .

It is not a de Polignac number, because 21309093 - 2⁵ = 21309061 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309023) 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, 90948 + ... + 91181.

It is an arithmetic number, because the mean of its divisors is an integer number (2762305).

Almost surely, 2^21309093 is an apocalyptic number.

It is an amenable number.

21309093 is a deficient number, since it is larger than the sum of its proper divisors (11838567).

21309093 is a wasteful number, since it uses less digits than its factorization.

21309093 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182148 (or 182145 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 27.

The square root of 21309093 is about 4616.1773146187. The cubic root of 21309093 is about 277.2394242510.

The spelling of 21309093 in words is "twenty-one million, three hundred nine thousand, ninety-three".