21023135280 has 560 divisors, whose sum is σ = 87434403840. Its totient is φ = 4594309632.

The previous prime is 21023135279. The next prime is 21023135291. The reversal of 21023135280 is 8253132012.

21023135280 is a `hidden beast` number, since 2 + 1 + 0 + 231 + 352 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (560).

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 111 ways as a sum of consecutive naturals, for example, 9388401 + ... + 9390639.

It is an arithmetic number, because the mean of its divisors is an integer number (156132864).

Almost surely, 2^21023135280 is an apocalyptic number.

21023135280 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 21023135280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43717201920).

21023135280 is an abundant number, since it is smaller than the sum of its proper divisors (66411268560).

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

21023135280 is a wasteful number, since it uses less digits than its factorization.

21023135280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2300 (or 2279 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

Adding to 21023135280 its reverse (8253132012), we get a palindrome (29276267292).

The spelling of 21023135280 in words is "twenty-one billion, twenty-three million, one hundred thirty-five thousand, two hundred eighty".