1221002102100 has 144 divisors (see below), whose sum is σ = 3900360360960. Its totient is φ = 292434172800.

The previous prime is 1221002102053. The next prime is 1221002102101. The reversal of 1221002102100 is 12012001221.

It is a super-2 number, since 2×1221002102100² (a number of 25 digits) contains 22 as substring.

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 (1221002102101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1955020 + ... + 2502819.

It is an arithmetic number, because the mean of its divisors is an integer number (27085835840).

Almost surely, 2^{1221002102100} is an apocalyptic number.

1221002102100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221002102100 is an abundant number, since it is smaller than the sum of its proper divisors (2679358258860).

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

1221002102100 is a wasteful number, since it uses less digits than its factorization.

1221002102100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4457950 (or 4457943 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 1221002102100 its reverse (12012001221), we get a palindrome (1233014103321).

The spelling of 1221002102100 in words is "one trillion, two hundred twenty-one billion, two million, one hundred two thousand, one hundred".