21319381440 has 672 divisors, whose sum is σ = 88669002240. Its totient is φ = 4774588416.

The previous prime is 21319381423. The next prime is 21319381483. The reversal of 21319381440 is 4418391312.

21319381440 is a `hidden beast` number, since 2 + 131 + 9 + 3 + 81 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

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 = 21319381395 and 21319381404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 28848591 + ... + 28849329.

It is an arithmetic number, because the mean of its divisors is an integer number (131947920).

Almost surely, 2^21319381440 is an apocalyptic number.

21319381440 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 21319381440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44334501120).

21319381440 is an abundant number, since it is smaller than the sum of its proper divisors (67349620800).

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

21319381440 is an equidigital number, since it uses as much as digits as its factorization.

21319381440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 831 (or 809 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The spelling of 21319381440 in words is "twenty-one billion, three hundred nineteen million, three hundred eighty-one thousand, four hundred forty".