21081188744 has 64 divisors (see below), whose sum is σ = 49456483200. Its totient is φ = 8184153600.

The previous prime is 21081188719. The next prime is 21081188761. The reversal of 21081188744 is 44788118012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a junction number, because it is equal to n+sod(n) for n = 21081188695 and 21081188704.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 112202 + ... + 233990.

It is an arithmetic number, because the mean of its divisors is an integer number (772757550).

Almost surely, 2^21081188744 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21081188744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24728241600).

21081188744 is an abundant number, since it is smaller than the sum of its proper divisors (28375294456).

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

21081188744 is a wasteful number, since it uses less digits than its factorization.

21081188744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122094 (or 122090 counting only the distinct ones).

The product of its (nonzero) digits is 114688, while the sum is 44.

The spelling of 21081188744 in words is "twenty-one billion, eighty-one million, one hundred eighty-eight thousand, seven hundred forty-four".