21105349 has 4 divisors (see below), whose sum is σ = 21292236. Its totient is φ = 20918464.

The previous prime is 21105341. The next prime is 21105361. The reversal of 21105349 is 94350112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 174724 + 20930625 = 418^2 + 4575^2 .

It is a cyclic number.

It is not a de Polignac number, because 21105349 - 2³ = 21105341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105341) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93274 + ... + 93499.

It is an arithmetic number, because the mean of its divisors is an integer number (5323059).

Almost surely, 2^21105349 is an apocalyptic number.

It is an amenable number.

21105349 is a deficient number, since it is larger than the sum of its proper divisors (186887).

21105349 is a wasteful number, since it uses less digits than its factorization.

21105349 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186886.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21105349 is about 4594.0558333568. The cubic root of 21105349 is about 276.3529973627.

The spelling of 21105349 in words is "twenty-one million, one hundred five thousand, three hundred forty-nine".