21581071546440 has 384 divisors, whose sum is σ = 76292814988800. Its totient is φ = 4868870307840.

The previous prime is 21581071546427. The next prime is 21581071546459. The reversal of 21581071546440 is 4464517018512.

It is a self number, because there is not a number n which added to its sum of digits gives 21581071546440.

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, 301919905 + ... + 301991375.

It is an arithmetic number, because the mean of its divisors is an integer number (198679205700).

Almost surely, 2^{21581071546440} is an apocalyptic number.

21581071546440 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 21581071546440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38146407494400).

21581071546440 is an abundant number, since it is smaller than the sum of its proper divisors (54711743442360).

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

21581071546440 is a wasteful number, since it uses less digits than its factorization.

21581071546440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72165 (or 72154 counting only the distinct ones).

The product of its (nonzero) digits is 1075200, while the sum is 48.

The spelling of 21581071546440 in words is "twenty-one trillion, five hundred eighty-one billion, seventy-one million, five hundred forty-six thousand, four hundred forty".