21320250 has 128 divisors (see below), whose sum is σ = 63258624. Its totient is φ = 4680000.

The previous prime is 21320239. The next prime is 21320267. The reversal of 21320250 is 5202312.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 162685 + ... + 162815.

It is an arithmetic number, because the mean of its divisors is an integer number (494208).

Almost surely, 2^21320250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21320250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31629312).

21320250 is an abundant number, since it is smaller than the sum of its proper divisors (41938374).

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

21320250 is a wasteful number, since it uses less digits than its factorization.

21320250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189 (or 179 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21320250 is about 4617.3856239218. The cubic root of 21320250 is about 277.2878014168.

Adding to 21320250 its reverse (5202312), we get a palindrome (26522562).

The spelling of 21320250 in words is "twenty-one million, three hundred twenty thousand, two hundred fifty".