21909025280 has 160 divisors (see below), whose sum is σ = 53761809024. Its totient is φ = 8560705536.

The previous prime is 21909025253. The next prime is 21909025297. The reversal of 21909025280 is 8252090912.

It is a tau number, because it is divible by the number of its divisors (160).

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, 20610029 + ... + 20611091.

Almost surely, 2^21909025280 is an apocalyptic number.

21909025280 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 21909025280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26880904512).

21909025280 is an abundant number, since it is smaller than the sum of its proper divisors (31852783744).

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

21909025280 is an equidigital number, since it uses as much as digits as its factorization.

21909025280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1266 (or 1250 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 38.

The spelling of 21909025280 in words is "twenty-one billion, nine hundred nine million, twenty-five thousand, two hundred eighty".