21235242500 has 60 divisors (see below), whose sum is σ = 46848800460. Its totient is φ = 8418816000.

The previous prime is 21235242491. The next prime is 21235242503. The reversal of 21235242500 is 524253212.

It can be written as a sum of positive squares in 10 ways, for example, as 19983215044 + 1252027456 = 141362^2 + 35384^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21235242500.

It is not an unprimeable number, because it can be changed into a prime (21235242503) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 244916 + ... + 320084.

It is an arithmetic number, because the mean of its divisors is an integer number (780813341).

Almost surely, 2^21235242500 is an apocalyptic number.

21235242500 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 21235242500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23424400230).

21235242500 is an abundant number, since it is smaller than the sum of its proper divisors (25613557960).

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

21235242500 is a wasteful number, since it uses less digits than its factorization.

21235242500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75306 (or 75289 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 26.

Adding to 21235242500 its reverse (524253212), we get a palindrome (21759495712).

The spelling of 21235242500 in words is "twenty-one billion, two hundred thirty-five million, two hundred forty-two thousand, five hundred".