21256738800 has 240 divisors, whose sum is σ = 78653037312. Its totient is φ = 4849971200.

The previous prime is 21256738753. The next prime is 21256738807. The reversal of 21256738800 is 883765212.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-2 number, since 2×21256738800² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256738807) 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, 177037 + ... + 271763.

Almost surely, 2^21256738800 is an apocalyptic number.

21256738800 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 21256738800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39326518656).

21256738800 is an abundant number, since it is smaller than the sum of its proper divisors (57396298512).

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

21256738800 is a wasteful number, since it uses less digits than its factorization.

21256738800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94776 (or 94765 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 42.

The spelling of 21256738800 in words is "twenty-one billion, two hundred fifty-six million, seven hundred thirty-eight thousand, eight hundred".