21513011212 has 48 divisors (see below), whose sum is σ = 49407886080. Its totient is φ = 7940548800.

The previous prime is 21513011197. The next prime is 21513011213. The reversal of 21513011212 is 21211031512.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a self number, because there is not a number n which added to its sum of digits gives 21513011212.

It is not an unprimeable number, because it can be changed into a prime (21513011213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1832239 + ... + 1843942.

It is an arithmetic number, because the mean of its divisors is an integer number (1029330960).

Almost surely, 2^21513011212 is an apocalyptic number.

21513011212 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21513011212 is an abundant number, since it is smaller than the sum of its proper divisors (27894874868).

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

21513011212 is a wasteful number, since it uses less digits than its factorization.

21513011212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3676222 (or 3676220 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 19.

Adding to 21513011212 its reverse (21211031512), we get a palindrome (42724042724).

The spelling of 21513011212 in words is "twenty-one billion, five hundred thirteen million, eleven thousand, two hundred twelve".