21201209984 has 32 divisors (see below), whose sum is σ = 42296538900. Its totient is φ = 10585608192.

The previous prime is 21201209963. The next prime is 21201209993. The reversal of 21201209984 is 48990210212.

It can be written as a sum of positive squares in 2 ways, for example, as 20198094400 + 1003115584 = 142120^2 + 31672^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a super-2 number, since 2×21201209984² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26057 + ... + 207560.

Almost surely, 2^21201209984 is an apocalyptic number.

It is an amenable number.

21201209984 is a deficient number, since it is larger than the sum of its proper divisors (21095328916).

21201209984 is an equidigital number, since it uses as much as digits as its factorization.

21201209984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234340 (or 234328 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 38.

The spelling of 21201209984 in words is "twenty-one billion, two hundred one million, two hundred nine thousand, nine hundred eighty-four".