21539258 has 16 divisors (see below), whose sum is σ = 34903176. Its totient is φ = 9910080.

The previous prime is 21539251. The next prime is 21539263. The reversal of 21539258 is 85293512.

It can be written as a sum of positive squares in 4 ways, for example, as 17032129 + 4507129 = 4127^2 + 2123^2 .

It is not an unprimeable number, because it can be changed into a prime (21539251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8588 + ... + 10808.

Almost surely, 2^21539258 is an apocalyptic number.

21539258 is a deficient number, since it is larger than the sum of its proper divisors (13363918).

21539258 is a wasteful number, since it uses less digits than its factorization.

21539258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2609.

The product of its digits is 21600, while the sum is 35.

The square root of 21539258 is about 4641.0406160688. The cubic root of 21539258 is about 278.2340299372.

It can be divided in two parts, 2153 and 9258, that added together give a palindrome (11411).

The spelling of 21539258 in words is "twenty-one million, five hundred thirty-nine thousand, two hundred fifty-eight".