21505580460 has 384 divisors, whose sum is σ = 85191321600. Its totient is φ = 4380687360.

The previous prime is 21505580441. The next prime is 21505580461. The reversal of 21505580460 is 6408550512.

21505580460 is a `hidden beast` number, since 2 + 15 + 0 + 5 + 580 + 4 + 60 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21505580461) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1417515 + ... + 1432605.

It is an arithmetic number, because the mean of its divisors is an integer number (221852400).

Almost surely, 2^21505580460 is an apocalyptic number.

21505580460 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 21505580460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42595660800).

21505580460 is an abundant number, since it is smaller than the sum of its proper divisors (63685741140).

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

21505580460 is a wasteful number, since it uses less digits than its factorization.

21505580460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15158 (or 15150 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 36.

The spelling of 21505580460 in words is "twenty-one billion, five hundred five million, five hundred eighty thousand, four hundred sixty".