21258 has 12 divisors (see below), whose sum is σ = 46098. Its totient is φ = 7080.

The previous prime is 21247. The next prime is 21269. The reversal of 21258 is 85212.

It is an interprime number because it is at equal distance from previous prime (21247) and next prime (21269).

It can be written as a sum of positive squares in only one way, i.e., 13689 + 7569 = 117^2 + 87^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1181 = 21258 / (2 + 1 + 2 + 5 + 8).

It is a d-powerful number, because it can be written as 2¹⁰ + 1 + 2¹² + 5⁶ + 8³ .

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 21258.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 573 + ... + 608.

2²¹²⁵⁸ is an apocalyptic number.

21258 is an abundant number, since it is smaller than the sum of its proper divisors (24840).

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

21258 is a wasteful number, since it uses less digits than its factorization.

21258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1189 (or 1186 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21258 is about 145.8012345627. The cubic root of 21258 is about 27.7017667117.

The spelling of 21258 in words is "twenty-one thousand, two hundred fifty-eight".