11311212221 has 16 divisors (see below), whose sum is σ = 12365337600. Its totient is φ = 10310409648.

The previous prime is 11311212217. The next prime is 11311212223. The reversal of 11311212221 is 12221211311.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 11311212221 - 2² = 11311212217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 11311212221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11311212223) 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, 48581 + ... + 158058.

It is an arithmetic number, because the mean of its divisors is an integer number (772833600).

Almost surely, 2^11311212221 is an apocalyptic number.

It is an amenable number.

11311212221 is a deficient number, since it is larger than the sum of its proper divisors (1054125379).

11311212221 is a wasteful number, since it uses less digits than its factorization.

11311212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206768.

The product of its digits is 48, while the sum is 17.

Adding to 11311212221 its reverse (12221211311), we get a palindrome (23532423532).

The spelling of 11311212221 in words is "eleven billion, three hundred eleven million, two hundred twelve thousand, two hundred twenty-one".