21002397685668 has 324 divisors, whose sum is σ = 62759604398400. Its totient is φ = 5904793702080.

The previous prime is 21002397685639. The next prime is 21002397685673. The reversal of 21002397685668 is 86658679320012.

It is a happy number.

21002397685668 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 2 + 3 + 9 + 7 + 68 + 566 + 8 = 666.

It is a super-2 number, since 2×21002397685668² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

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 107 ways as a sum of consecutive naturals, for example, 5326500105 + ... + 5326504047.

Almost surely, 2^{21002397685668} is an apocalyptic number.

21002397685668 is a gapful number since it is divisible by the number (28) 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 21002397685668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31379802199200).

21002397685668 is an abundant number, since it is smaller than the sum of its proper divisors (41757206712732).

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

21002397685668 is a wasteful number, since it uses less digits than its factorization.

21002397685668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4708 (or 4625 counting only the distinct ones).

The product of its (nonzero) digits is 52254720, while the sum is 63.

The spelling of 21002397685668 in words is "twenty-one trillion, two billion, three hundred ninety-seven million, six hundred eighty-five thousand, six hundred sixty-eight".