21256240320 has 448 divisors, whose sum is σ = 86777779200. Its totient is φ = 4857449472.

The previous prime is 21256240283. The next prime is 21256240339. The reversal of 21256240320 is 2304265212.

It is a happy number.

21256240320 is a `hidden beast` number, since 2 + 1 + 2 + 5 + 624 + 0 + 32 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4896711 + ... + 4901049.

It is an arithmetic number, because the mean of its divisors is an integer number (193700400).

Almost surely, 2^21256240320 is an apocalyptic number.

21256240320 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 21256240320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43388889600).

21256240320 is an abundant number, since it is smaller than the sum of its proper divisors (65521538880).

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

21256240320 is an frugal number, since it uses more digits than its factorization.

21256240320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4384 (or 4356 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The spelling of 21256240320 in words is "twenty-one billion, two hundred fifty-six million, two hundred forty thousand, three hundred twenty".