21125250 has 96 divisors (see below), whose sum is σ = 58771440. Its totient is φ = 5472000.

The previous prime is 21125239. The next prime is 21125257. The reversal of 21125250 is 5252112.

It can be written as a sum of positive squares in 8 ways, for example, as 522729 + 20602521 = 723^2 + 4539^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21125257) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 92136 + ... + 92364.

Almost surely, 2^21125250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21125250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29385720).

21125250 is an abundant number, since it is smaller than the sum of its proper divisors (37646190).

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

21125250 is a wasteful number, since it uses less digits than its factorization.

21125250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21125250 is about 4596.2212740468. The cubic root of 21125250 is about 276.4398311678.

Adding to 21125250 its reverse (5252112), we get a palindrome (26377362).

The spelling of 21125250 in words is "twenty-one million, one hundred twenty-five thousand, two hundred fifty".