21275181 has 6 divisors (see below), whose sum is σ = 30730830. Its totient is φ = 14183448.

The previous prime is 21275179. The next prime is 21275197. The reversal of 21275181 is 18157212.

It can be written as a sum of positive squares in only one way, i.e., 15729156 + 5546025 = 3966^2 + 2355^2 .

It is not a de Polignac number, because 21275181 - 2¹ = 21275179 is a prime.

It is a super-2 number, since 2×21275181² = 905266653165522, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21275171) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1181946 + ... + 1181963.

It is an arithmetic number, because the mean of its divisors is an integer number (5121805).

Almost surely, 2^21275181 is an apocalyptic number.

It is an amenable number.

21275181 is a deficient number, since it is larger than the sum of its proper divisors (9455649).

21275181 is a wasteful number, since it uses less digits than its factorization.

21275181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2363915 (or 2363912 counting only the distinct ones).

The product of its digits is 1120, while the sum is 27.

The square root of 21275181 is about 4612.5026829260. The cubic root of 21275181 is about 277.0922768151.

The spelling of 21275181 in words is "twenty-one million, two hundred seventy-five thousand, one hundred eighty-one".