21245130 has 48 divisors (see below), whose sum is σ = 55752840. Its totient is φ = 5612544.

The previous prime is 21245129. The next prime is 21245153. The reversal of 21245130 is 3154212.

21245130 is a `hidden beast` number, since 212 + 451 + 3 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 15000129 + 6245001 = 3873^2 + 2499^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9126 + ... + 11214.

Almost surely, 2^21245130 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21245130, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27876420).

21245130 is an abundant number, since it is smaller than the sum of its proper divisors (34507710).

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

21245130 is a wasteful number, since it uses less digits than its factorization.

21245130 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2215 (or 2212 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21245130 is about 4609.2439727140. The cubic root of 21245130 is about 276.9617518990.

Adding to 21245130 its reverse (3154212), we get a palindrome (24399342).

The spelling of 21245130 in words is "twenty-one million, two hundred forty-five thousand, one hundred thirty".