21530258 has 4 divisors (see below), whose sum is σ = 32295390. Its totient is φ = 10765128.

The previous prime is 21530251. The next prime is 21530261. The reversal of 21530258 is 85203512.

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

It can be written as a sum of positive squares in only one way, i.e., 21224449 + 305809 = 4607^2 + 553^2 .

It is not an unprimeable number, because it can be changed into a prime (21530251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5382563 + ... + 5382566.

Almost surely, 2^21530258 is an apocalyptic number.

21530258 is a deficient number, since it is larger than the sum of its proper divisors (10765132).

21530258 is a wasteful number, since it uses less digits than its factorization.

21530258 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10765131.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 21530258 is about 4640.0709046307. The cubic root of 21530258 is about 278.1952719459.

The spelling of 21530258 in words is "twenty-one million, five hundred thirty thousand, two hundred fifty-eight".