21258000 has 120 divisors (see below), whose sum is σ = 74309976. Its totient is φ = 5664000.

The previous prime is 21257993. The next prime is 21258001. The reversal of 21258000 is 85212.

It can be written as a sum of positive squares in 4 ways, for example, as 24336 + 21233664 = 156^2 + 4608^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21258001) 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, 17410 + ... + 18590.

Almost surely, 2^21258000 is an apocalyptic number.

21258000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21258000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37154988).

21258000 is an abundant number, since it is smaller than the sum of its proper divisors (53051976).

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

21258000 is a wasteful number, since it uses less digits than its factorization.

21258000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1210 (or 1191 counting only the distinct ones).

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

The square root of 21258000 is about 4610.6398688252. The cubic root of 21258000 is about 277.0176671168.

The spelling of 21258000 in words is "twenty-one million, two hundred fifty-eight thousand".