21118371840 has 768 divisors, whose sum is σ = 81234316800. Its totient is φ = 5255331840.

The previous prime is 21118371823. The next prime is 21118371889. The reversal of 21118371840 is 4817381112.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21118371795 and 21118371804.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 515082220 + ... + 515082260.

It is an arithmetic number, because the mean of its divisors is an integer number (105773850).

Almost surely, 2^21118371840 is an apocalyptic number.

21118371840 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 21118371840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40617158400).

21118371840 is an abundant number, since it is smaller than the sum of its proper divisors (60115944960).

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

21118371840 is an frugal number, since it uses more digits than its factorization.

21118371840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112 (or 74 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The spelling of 21118371840 in words is "twenty-one billion, one hundred eighteen million, three hundred seventy-one thousand, eight hundred forty".