1221000100120 has 16 divisors (see below), whose sum is σ = 2747250225360. Its totient is φ = 488400040032.

The previous prime is 1221000100091. The next prime is 1221000100121. The reversal of 1221000100120 is 210010001221.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 1221000100097 and 1221000100106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221000100121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15262501212 + ... + 15262501291.

It is an arithmetic number, because the mean of its divisors is an integer number (171703139085).

Almost surely, 2^{1221000100120} is an apocalyptic number.

1221000100120 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221000100120 is an abundant number, since it is smaller than the sum of its proper divisors (1526250125240).

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

1221000100120 is a wasteful number, since it uses less digits than its factorization.

1221000100120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30525002514 (or 30525002510 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 1221000100120 its reverse (210010001221), we get a palindrome (1431010101341).

The spelling of 1221000100120 in words is "one trillion, two hundred twenty-one billion, one hundred thousand, one hundred twenty".