21158029440 has 448 divisors, whose sum is σ = 76758111000. Its totient is φ = 5573836800.

The previous prime is 21158029423. The next prime is 21158029441. The reversal of 21158029440 is 4492085112.

21158029440 is a `hidden beast` number, since 2 + 11 + 580 + 29 + 4 + 40 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 20881406016 + 276623424 = 144504^2 + 16632^2 .

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 = 21158029395 and 21158029404.

It is not an unprimeable number, because it can be changed into a prime (21158029441) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 47122336 + ... + 47122784.

Almost surely, 2^21158029440 is an apocalyptic number.

21158029440 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 21158029440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38379055500).

21158029440 is an abundant number, since it is smaller than the sum of its proper divisors (55600081560).

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

21158029440 is an equidigital number, since it uses as much as digits as its factorization.

21158029440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 587 (or 560 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The spelling of 21158029440 in words is "twenty-one billion, one hundred fifty-eight million, twenty-nine thousand, four hundred forty".