21181365280 has 24 divisors (see below), whose sum is σ = 50040975852. Its totient is φ = 8472546048.

The previous prime is 21181365239. The next prime is 21181365287. The reversal of 21181365280 is 8256318112.

It can be written as a sum of positive squares in 2 ways, for example, as 18627882256 + 2553483024 = 136484^2 + 50532^2 .

It is not an unprimeable number, because it can be changed into a prime (21181365287) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66191607 + ... + 66191926.

Almost surely, 2^21181365280 is an apocalyptic number.

21181365280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21181365280 is an abundant number, since it is smaller than the sum of its proper divisors (28859610572).

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

21181365280 is a wasteful number, since it uses less digits than its factorization.

21181365280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132383548 (or 132383540 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The spelling of 21181365280 in words is "twenty-one billion, one hundred eighty-one million, three hundred sixty-five thousand, two hundred eighty".