21135699684 has 432 divisors, whose sum is σ = 66674881728. Its totient is φ = 5833555200.

The previous prime is 21135699659. The next prime is 21135699691. The reversal of 21135699684 is 48699653112.

21135699684 is a `hidden beast` number, since 2 + 1 + 13 + 569 + 9 + 68 + 4 = 666.

It is a super-2 number, since 2×21135699684² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

Its product of digits (2799360) is a multiple of the sum of its prime divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 21135699684.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 681796749 + ... + 681796779.

It is an arithmetic number, because the mean of its divisors is an integer number (154340004).

Almost surely, 2^21135699684 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21135699684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33337440864).

21135699684 is an abundant number, since it is smaller than the sum of its proper divisors (45539182044).

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

21135699684 is a wasteful number, since it uses less digits than its factorization.

21135699684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131 (or 64 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 54.

The spelling of 21135699684 in words is "twenty-one billion, one hundred thirty-five million, six hundred ninety-nine thousand, six hundred eighty-four".