21135258 has 48 divisors (see below), whose sum is σ = 49888800. Its totient is φ = 6441120.

The previous prime is 21135227. The next prime is 21135259. The reversal of 21135258 is 85253112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21135259) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8853 + ... + 10983.

It is an arithmetic number, because the mean of its divisors is an integer number (1039350).

Almost surely, 2^21135258 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21135258, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24944400).

21135258 is an abundant number, since it is smaller than the sum of its proper divisors (28753542).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21135258 is a wasteful number, since it uses less digits than its factorization.

21135258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2187 (or 2184 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21135258 is about 4597.3098655627. The cubic root of 21135258 is about 276.4834783523.

The spelling of 21135258 in words is "twenty-one million, one hundred thirty-five thousand, two hundred fifty-eight".