21205135212 has 48 divisors (see below), whose sum is σ = 52306450560. Its totient is φ = 6667602048.

The previous prime is 21205135201. The next prime is 21205135213. The reversal of 21205135212 is 21253150212.

It is not an unprimeable number, because it can be changed into a prime (21205135213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 146458 + ... + 252705.

It is an arithmetic number, because the mean of its divisors is an integer number (1089717720).

Almost surely, 2^21205135212 is an apocalyptic number.

It is an amenable number.

21205135212 is an abundant number, since it is smaller than the sum of its proper divisors (31101315348).

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

21205135212 is a wasteful number, since it uses less digits than its factorization.

21205135212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399422 (or 399420 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

Adding to 21205135212 its reverse (21253150212), we get a palindrome (42458285424).

The spelling of 21205135212 in words is "twenty-one billion, two hundred five million, one hundred thirty-five thousand, two hundred twelve".