21250500 has 96 divisors (see below), whose sum is σ = 64017408. Its totient is φ = 5472000.

The previous prime is 21250499. The next prime is 21250511. The reversal of 21250500 is 505212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21250500.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 46272 + ... + 46728.

It is an arithmetic number, because the mean of its divisors is an integer number (666848).

Almost surely, 2^21250500 is an apocalyptic number.

21250500 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 21250500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32008704).

21250500 is an abundant number, since it is smaller than the sum of its proper divisors (42766908).

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

21250500 is a wasteful number, since it uses less digits than its factorization.

21250500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 510 (or 498 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 21250500 is about 4609.8264609419. The cubic root of 21250500 is about 276.9850852357.

Adding to 21250500 its reverse (505212), we get a palindrome (21755712).

The spelling of 21250500 in words is "twenty-one million, two hundred fifty thousand, five hundred".