21205985472 has 84 divisors (see below), whose sum is σ = 69466445776. Its totient is φ = 6058851840.

The previous prime is 21205985467. The next prime is 21205985473. The reversal of 21205985472 is 27458950212.

21205985472 is a `hidden beast` number, since 2 + 1 + 2 + 0 + 598 + 54 + 7 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (84).

It is not an unprimeable number, because it can be changed into a prime (21205985473) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2625679 + ... + 2633742.

Almost surely, 2^21205985472 is an apocalyptic number.

It is an amenable number.

21205985472 is an abundant number, since it is smaller than the sum of its proper divisors (48260460304).

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

21205985472 is a wasteful number, since it uses less digits than its factorization.

21205985472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5259446 (or 5259433 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 21205985472 in words is "twenty-one billion, two hundred five million, nine hundred eighty-five thousand, four hundred seventy-two".