21265403250 has 768 divisors, whose sum is σ = 74204282880. Its totient is φ = 3934656000.

The previous prime is 21265403249. The next prime is 21265403261. The reversal of 21265403250 is 5230456212.

It is a super-2 number, since 2×21265403250² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 685980735 + ... + 685980765.

It is an arithmetic number, because the mean of its divisors is an integer number (96620160).

Almost surely, 2^21265403250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21265403250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37102141440).

21265403250 is an abundant number, since it is smaller than the sum of its proper divisors (52938879630).

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

21265403250 is a wasteful number, since it uses less digits than its factorization.

21265403250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 103 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 30.

Adding to 21265403250 its reverse (5230456212), we get a palindrome (26495859462).

The spelling of 21265403250 in words is "twenty-one billion, two hundred sixty-five million, four hundred three thousand, two hundred fifty".