21099900019968 has 972 divisors, whose sum is σ = 78974130379872. Its totient is φ = 5303232000000.

The previous prime is 21099900019963. The next prime is 21099900020041. The reversal of 21099900019968 is 86991000999012.

21099900019968 is a `hidden beast` number, since 210 + 99 + 90 + 0 + 0 + 199 + 68 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099900019963) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 1875374343 + ... + 1875385593.

Almost surely, 2^{21099900019968} is an apocalyptic number.

21099900019968 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 21099900019968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39487065189936).

21099900019968 is an abundant number, since it is smaller than the sum of its proper divisors (57874230359904).

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

21099900019968 is a wasteful number, since it uses less digits than its factorization.

21099900019968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11364 (or 11305 counting only the distinct ones).

The product of its (nonzero) digits is 5668704, while the sum is 63.

The spelling of 21099900019968 in words is "twenty-one trillion, ninety-nine billion, nine hundred million, nineteen thousand, nine hundred sixty-eight".