21345221280 has 96 divisors (see below), whose sum is σ = 67291560000. Its totient is φ = 5687478272.

The previous prime is 21345221251. The next prime is 21345221291. The reversal of 21345221280 is 8212254312.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 601471 + ... + 635969.

It is an arithmetic number, because the mean of its divisors is an integer number (700953750).

Almost surely, 2^21345221280 is an apocalyptic number.

21345221280 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 21345221280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33645780000).

21345221280 is an abundant number, since it is smaller than the sum of its proper divisors (45946338720).

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

21345221280 is a wasteful number, since it uses less digits than its factorization.

21345221280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35806 (or 35798 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

Adding to 21345221280 its reverse (8212254312), we get a palindrome (29557475592).

The spelling of 21345221280 in words is "twenty-one billion, three hundred forty-five million, two hundred twenty-one thousand, two hundred eighty".