21505332380 has 48 divisors (see below), whose sum is σ = 51702442176. Its totient is φ = 7360450560.

The previous prime is 21505332379. The next prime is 21505332439. The reversal of 21505332380 is 8323350512.

It is a congruent number.

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, 52331 + ... + 213890.

It is an arithmetic number, because the mean of its divisors is an integer number (1077134212).

Almost surely, 2^21505332380 is an apocalyptic number.

21505332380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21505332380 is an abundant number, since it is smaller than the sum of its proper divisors (30197109796).

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

21505332380 is a wasteful number, since it uses less digits than its factorization.

21505332380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266814 (or 266812 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 32.

Adding to 21505332380 its reverse (8323350512), we get a palindrome (29828682892).

The spelling of 21505332380 in words is "twenty-one billion, five hundred five million, three hundred thirty-two thousand, three hundred eighty".