21134257 has 4 divisors (see below), whose sum is σ = 21186340. Its totient is φ = 21082176.

The previous prime is 21134249. The next prime is 21134273. The reversal of 21134257 is 75243112.

It is a happy number.

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 20286016 + 848241 = 4504^2 + 921^2 .

It is a cyclic number.

It is not a de Polignac number, because 21134257 - 2³ = 21134249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21134237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25428 + ... + 26245.

It is an arithmetic number, because the mean of its divisors is an integer number (5296585).

Almost surely, 2^21134257 is an apocalyptic number.

It is an amenable number.

21134257 is a deficient number, since it is larger than the sum of its proper divisors (52083).

21134257 is an equidigital number, since it uses as much as digits as its factorization.

21134257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52082.

The product of its digits is 1680, while the sum is 25.

The square root of 21134257 is about 4597.2009962585. The cubic root of 21134257 is about 276.4791133818.

Adding to 21134257 its reverse (75243112), we get a palindrome (96377369).

It can be divided in two parts, 211 and 34257, that multiplied together give a palindrome (7228227).

The spelling of 21134257 in words is "twenty-one million, one hundred thirty-four thousand, two hundred fifty-seven".