21510543440 has 80 divisors (see below), whose sum is σ = 50766988800. Its totient is φ = 8474858496.

The previous prime is 21510543427. The next prime is 21510543463. The reversal of 21510543440 is 4434501512.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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, 2770604 + ... + 2778356.

It is an arithmetic number, because the mean of its divisors is an integer number (634587360).

Almost surely, 2^21510543440 is an apocalyptic number.

21510543440 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 21510543440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25383494400).

21510543440 is an abundant number, since it is smaller than the sum of its proper divisors (29256445360).

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

21510543440 is a wasteful number, since it uses less digits than its factorization.

21510543440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8284 (or 8278 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 29.

The spelling of 21510543440 in words is "twenty-one billion, five hundred ten million, five hundred forty-three thousand, four hundred forty".