21203311212 has 144 divisors (see below), whose sum is σ = 57953750400. Its totient is φ = 6514456320.

The previous prime is 21203311201. The next prime is 21203311229. The reversal of 21203311212 is 21211330212.

21203311212 is a `hidden beast` number, since 2 + 120 + 331 + 1 + 212 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13095739 + ... + 13097357.

It is an arithmetic number, because the mean of its divisors is an integer number (402456600).

Almost surely, 2^21203311212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21203311212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28976875200).

21203311212 is an abundant number, since it is smaller than the sum of its proper divisors (36750439188).

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

21203311212 is a wasteful number, since it uses less digits than its factorization.

21203311212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2156 (or 2151 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21203311212 its reverse (21211330212), we get a palindrome (42414641424).

The spelling of 21203311212 in words is "twenty-one billion, two hundred three million, three hundred eleven thousand, two hundred twelve".