21253573800 has 240 divisors, whose sum is σ = 74651276700. Its totient is φ = 5603558400.

The previous prime is 21253573787. The next prime is 21253573801. The reversal of 21253573800 is 837535212.

It is a happy number.

21253573800 is a `hidden beast` number, since 2 + 1 + 2 + 5 + 3 + 573 + 80 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 10678742244 + 10574831556 = 103338^2 + 102834^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21253573801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 1434430 + ... + 1449170.

Almost surely, 2^21253573800 is an apocalyptic number.

21253573800 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 21253573800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37325638350).

21253573800 is an abundant number, since it is smaller than the sum of its proper divisors (53397702900).

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

21253573800 is a wasteful number, since it uses less digits than its factorization.

21253573800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14858 (or 14840 counting only the distinct ones).

The product of its (nonzero) digits is 50400, while the sum is 36.

The spelling of 21253573800 in words is "twenty-one billion, two hundred fifty-three million, five hundred seventy-three thousand, eight hundred".