21183771420 has 288 divisors, whose sum is σ = 76812503040. Its totient is φ = 4620464640.

The previous prime is 21183771379. The next prime is 21183771457. The reversal of 21183771420 is 2417738112.

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 (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 20546305 + ... + 20547335.

It is an arithmetic number, because the mean of its divisors is an integer number (266710080).

Almost surely, 2^21183771420 is an apocalyptic number.

21183771420 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 21183771420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38406251520).

21183771420 is an abundant number, since it is smaller than the sum of its proper divisors (55628731620).

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

21183771420 is a wasteful number, since it uses less digits than its factorization.

21183771420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1785 (or 1780 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The spelling of 21183771420 in words is "twenty-one billion, one hundred eighty-three million, seven hundred seventy-one thousand, four hundred twenty".