1221111100100 has 36 divisors (see below), whose sum is σ = 2650032759444. Its totient is φ = 488403578880.

The previous prime is 1221111100093. The next prime is 1221111100117. The reversal of 1221111100100 is 10011111221.

It can be written as a sum of positive squares in 6 ways, for example, as 570662398084 + 650448702016 = 755422^2 + 806504^2 .

It is a super-2 number, since 2×1221111100100² (a number of 25 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 704984 + ... + 1714416.

Almost surely, 2^{1221111100100} is an apocalyptic number.

1221111100100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221111100100 is an abundant number, since it is smaller than the sum of its proper divisors (1428921659344).

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

1221111100100 is a wasteful number, since it uses less digits than its factorization.

1221111100100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1021544 (or 1021537 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 1221111100100 its reverse (10011111221), we get a palindrome (1231122211321).

The spelling of 1221111100100 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, one hundred thousand, one hundred".