1221201011100 has 72 divisors (see below), whose sum is σ = 4038104683648. Its totient is φ = 279131659200.

The previous prime is 1221201010993. The next prime is 1221201011101. The reversal of 1221201011100 is 11101021221.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221201011101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 290760046 + ... + 290764245.

Almost surely, 2^{1221201011100} is an apocalyptic number.

1221201011100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221201011100 is an abundant number, since it is smaller than the sum of its proper divisors (2816903672548).

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

1221201011100 is a wasteful number, since it uses less digits than its factorization.

1221201011100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581524315 (or 581524308 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 1221201011100 its reverse (11101021221), we get a palindrome (1232302032321).

The spelling of 1221201011100 in words is "one trillion, two hundred twenty-one billion, two hundred one million, eleven thousand, one hundred".