21121051551600 has 4320 divisors, whose sum is σ = 100512643350528. Its totient is φ = 3736212480000.

The previous prime is 21121051551583. The next prime is 21121051551653. The reversal of 21121051551600 is 615515012112.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 863 ways as a sum of consecutive naturals, for example, 77937459465 + ... + 77937459735.

Almost surely, 2^{21121051551600} is an apocalyptic number.

21121051551600 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 21121051551600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50256321675264).

21121051551600 is an abundant number, since it is smaller than the sum of its proper divisors (79391591798928).

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

21121051551600 is a wasteful number, since it uses less digits than its factorization.

21121051551600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397 (or 366 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 30.

Adding to 21121051551600 its reverse (615515012112), we get a palindrome (21736566563712).

The spelling of 21121051551600 in words is "twenty-one trillion, one hundred twenty-one billion, fifty-one million, five hundred fifty-one thousand, six hundred".