1221289356900 has 72 divisors (see below), whose sum is σ = 3655445411520. Its totient is φ = 314446912640.

The previous prime is 1221289356863. The next prime is 1221289356901. The reversal of 1221289356900 is 96539821221.

It is a happy number.

It is a super-2 number, since 2×1221289356900² (a number of 25 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221289356900.

It is not an unprimeable number, because it can be changed into a prime (1221289356901) 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, 70180344 + ... + 70197743.

It is an arithmetic number, because the mean of its divisors is an integer number (50770075160).

Almost surely, 2^{1221289356900} is an apocalyptic number.

1221289356900 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221289356900 is an abundant number, since it is smaller than the sum of its proper divisors (2434156054620).

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

1221289356900 is a wasteful number, since it uses less digits than its factorization.

1221289356900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140378133 (or 140378126 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 48.

The spelling of 1221289356900 in words is "one trillion, two hundred twenty-one billion, two hundred eighty-nine million, three hundred fifty-six thousand, nine hundred".