21512128135680 has 3840 divisors, whose sum is σ = 99761854832640. Its totient is φ = 4161798144000.

The previous prime is 21512128135669. The next prime is 21512128135723. The reversal of 21512128135680 is 8653182121512.

It is a happy number.

21512128135680 is a `hidden beast` number, since 2 + 1 + 5 + 1 + 2 + 1 + 2 + 81 + 3 + 568 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (3840).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 190372815304 + ... + 190372815416.

It is an arithmetic number, because the mean of its divisors is an integer number (25979649696).

Almost surely, 2^{21512128135680} is an apocalyptic number.

21512128135680 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 21512128135680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49880927416320).

21512128135680 is an abundant number, since it is smaller than the sum of its proper divisors (78249726696960).

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

21512128135680 is a wasteful number, since it uses less digits than its factorization.

21512128135680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323 (or 304 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 45.

The spelling of 21512128135680 in words is "twenty-one trillion, five hundred twelve billion, one hundred twenty-eight million, one hundred thirty-five thousand, six hundred eighty".