1221011000000 has 294 divisors, whose sum is σ = 3329331837132. Its totient is φ = 443960000000.

The previous prime is 1221010999981. The next prime is 1221011000039. The reversal of 1221011000000 is 1101221.

It is a Harshad number since it is a multiple of its sum of digits (8).

It is an unprimeable number.

It is a polite number, since it can be written in 41 ways as a sum of consecutive naturals, for example, 120994955 + ... + 121005045.

Almost surely, 2^{1221011000000} is an apocalyptic number.

1221011000000 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 1221011000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1664665918566).

1221011000000 is an abundant number, since it is smaller than the sum of its proper divisors (2108320837132).

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

1221011000000 is an frugal number, since it uses more digits than its factorization.

1221011000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10155 (or 10109 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 1221011000000 its reverse (1101221), we get a palindrome (1221012101221).

The spelling of 1221011000000 in words is "one trillion, two hundred twenty-one billion, eleven million", and thus it is an aban number.