21811935420 has 192 divisors, whose sum is σ = 76417044480. Its totient is φ = 5117126400.

The previous prime is 21811935413. The next prime is 21811935463. The reversal of 21811935420 is 2453911812.

21811935420 is a `hidden beast` number, since 2 + 18 + 11 + 93 + 542 + 0 = 666.

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

It is a congruent number.

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 63 ways as a sum of consecutive naturals, for example, 124914 + ... + 243366.

It is an arithmetic number, because the mean of its divisors is an integer number (398005440).

Almost surely, 2^21811935420 is an apocalyptic number.

21811935420 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 21811935420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38208522240).

21811935420 is an abundant number, since it is smaller than the sum of its proper divisors (54605109060).

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

21811935420 is a wasteful number, since it uses less digits than its factorization.

21811935420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118513 (or 118505 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The spelling of 21811935420 in words is "twenty-one billion, eight hundred eleven million, nine hundred thirty-five thousand, four hundred twenty".