21051561300 has 432 divisors, whose sum is σ = 78120624960. Its totient is φ = 4327680000.

The previous prime is 21051561287. The next prime is 21051561301. The reversal of 21051561300 is 316515012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051561301) by changing a digit.

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 143 ways as a sum of consecutive naturals, for example, 16331056 + ... + 16332344.

It is an arithmetic number, because the mean of its divisors is an integer number (180834780).

Almost surely, 2^21051561300 is an apocalyptic number.

21051561300 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 21051561300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39060312480).

21051561300 is an abundant number, since it is smaller than the sum of its proper divisors (57069063660).

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

21051561300 is a wasteful number, since it uses less digits than its factorization.

21051561300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1432 (or 1418 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 24.

The spelling of 21051561300 in words is "twenty-one billion, fifty-one million, five hundred sixty-one thousand, three hundred".