21261139200 has 1296 divisors, whose sum is σ = 94772267520. Its totient is φ = 4702924800.

The previous prime is 21261139183. The next prime is 21261139201. The reversal of 21261139200 is 293116212.

21261139200 is a `hidden beast` number, since 2 + 12 + 611 + 39 + 2 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1296).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261139201) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 685843185 + ... + 685843215.

Almost surely, 2^21261139200 is an apocalyptic number.

21261139200 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 21261139200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47386133760).

21261139200 is an abundant number, since it is smaller than the sum of its proper divisors (73511128320).

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

21261139200 is an frugal number, since it uses more digits than its factorization.

21261139200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

It can be divided in two parts, 21261 and 139200, that added together give a triangular number (160461 = T₅₆₆).

The spelling of 21261139200 in words is "twenty-one billion, two hundred sixty-one million, one hundred thirty-nine thousand, two hundred".