21271853 has 4 divisors (see below), whose sum is σ = 21427260. Its totient is φ = 21116448.

The previous prime is 21271843. The next prime is 21271883. The reversal of 21271853 is 35817212.

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 4313929 + 16957924 = 2077^2 + 4118^2 .

It is a cyclic number.

It is not a de Polignac number, because 21271853 - 2⁴ = 21271837 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 (21271843) 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 3 ways as a sum of consecutive naturals, for example, 77498 + ... + 77771.

It is an arithmetic number, because the mean of its divisors is an integer number (5356815).

Almost surely, 2^21271853 is an apocalyptic number.

It is an amenable number.

21271853 is a deficient number, since it is larger than the sum of its proper divisors (155407).

21271853 is a wasteful number, since it uses less digits than its factorization.

21271853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155406.

The product of its digits is 3360, while the sum is 29.

The square root of 21271853 is about 4612.1419102192. The cubic root of 21271853 is about 277.0778278791.

The spelling of 21271853 in words is "twenty-one million, two hundred seventy-one thousand, eight hundred fifty-three".