1221312135200 has 72 divisors (see below), whose sum is σ = 2982029801940. Its totient is φ = 488442675200.

The previous prime is 1221312135187. The next prime is 1221312135227. The reversal of 1221312135200 is 25312131221.

It can be written as a sum of positive squares in 6 ways, for example, as 179189662864 + 1042122472336 = 423308^2 + 1020844^2 .

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, 4745840 + ... + 4996560.

Almost surely, 2^{1221312135200} is an apocalyptic number.

1221312135200 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221312135200 is an abundant number, since it is smaller than the sum of its proper divisors (1760717666740).

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

1221312135200 is a wasteful number, since it uses less digits than its factorization.

1221312135200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256830 (or 256817 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

Adding to 1221312135200 its reverse (25312131221), we get a palindrome (1246624266421).

The spelling of 1221312135200 in words is "one trillion, two hundred twenty-one billion, three hundred twelve million, one hundred thirty-five thousand, two hundred".