21918929687928 has 1024 divisors, whose sum is σ = 81465753600000. Its totient is φ = 5410205498880.

The previous prime is 21918929687891. The next prime is 21918929687959. The reversal of 21918929687928 is 82978692981912.

21918929687928 is a `hidden beast` number, since 2 + 1 + 91 + 89 + 296 + 87 + 92 + 8 = 666.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 1518870873 + ... + 1518885303.

It is an arithmetic number, because the mean of its divisors is an integer number (79556400000).

Almost surely, 2^{21918929687928} is an apocalyptic number.

21918929687928 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 21918929687928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40732876800000).

21918929687928 is an abundant number, since it is smaller than the sum of its proper divisors (59546823912072).

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

21918929687928 is a wasteful number, since it uses less digits than its factorization.

21918929687928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14582 (or 14558 counting only the distinct ones).

The product of its digits is 1128701952, while the sum is 81.

The spelling of 21918929687928 in words is "twenty-one trillion, nine hundred eighteen billion, nine hundred twenty-nine million, six hundred eighty-seven thousand, nine hundred twenty-eight".