21161041440 has 1152 divisors, whose sum is σ = 91429502976. Its totient is φ = 4014489600.

The previous prime is 21161041423. The next prime is 21161041453. The reversal of 21161041440 is 4414016112.

It is a super-3 number, since 3×21161041440³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21161041440.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 289877244 + ... + 289877316.

It is an arithmetic number, because the mean of its divisors is an integer number (79365888).

Almost surely, 2^21161041440 is an apocalyptic number.

21161041440 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 21161041440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45714751488).

21161041440 is an abundant number, since it is smaller than the sum of its proper divisors (70268461536).

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

21161041440 is a wasteful number, since it uses less digits than its factorization.

21161041440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 155 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

Adding to 21161041440 its reverse (4414016112), we get a palindrome (25575057552).

The spelling of 21161041440 in words is "twenty-one billion, one hundred sixty-one million, forty-one thousand, four hundred forty".