21205446560 has 48 divisors (see below), whose sum is σ = 51262950816. Its totient is φ = 8284915968.

The previous prime is 21205446557. The next prime is 21205446569. The reversal of 21205446560 is 6564450212.

It is a self number, because there is not a number n which added to its sum of digits gives 21205446560.

It is not an unprimeable number, because it can be changed into a prime (21205446569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1534214 + ... + 1547973.

It is an arithmetic number, because the mean of its divisors is an integer number (1067978142).

Almost surely, 2^21205446560 is an apocalyptic number.

21205446560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21205446560 is an abundant number, since it is smaller than the sum of its proper divisors (30057504256).

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

21205446560 is a wasteful number, since it uses less digits than its factorization.

21205446560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3082245 (or 3082237 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 35.

Adding to 21205446560 its reverse (6564450212), we get a palindrome (27769896772).

The spelling of 21205446560 in words is "twenty-one billion, two hundred five million, four hundred forty-six thousand, five hundred sixty".