1221311000000 has 392 divisors, whose sum is σ = 3728751646368. Its totient is φ = 386496000000.

The previous prime is 1221310999943. The next prime is 1221311000081. The reversal of 1221311000000 is 1131221.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 90993290 + ... + 91006710.

Almost surely, 2^{1221311000000} is an apocalyptic number.

1221311000000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221311000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1864375823184).

1221311000000 is an abundant number, since it is smaller than the sum of its proper divisors (2507440646368).

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

1221311000000 is an frugal number, since it uses more digits than its factorization.

1221311000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13483 (or 13448 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 11.

Adding to 1221311000000 its reverse (1131221), we get a palindrome (1221312131221).

The spelling of 1221311000000 in words is "one trillion, two hundred twenty-one billion, three hundred eleven million", and thus it is an aban number.