1221131020156 has 6 divisors (see below), whose sum is σ = 2136979285280. Its totient is φ = 610565510076.

The previous prime is 1221131020069. The next prime is 1221131020157. The reversal of 1221131020156 is 6510201311221.

It is a self number, because there is not a number n which added to its sum of digits gives 1221131020156.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221131020157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 152641377516 + ... + 152641377523.

Almost surely, 2^{1221131020156} is an apocalyptic number.

It is an amenable number.

1221131020156 is a deficient number, since it is larger than the sum of its proper divisors (915848265124).

1221131020156 is a wasteful number, since it uses less digits than its factorization.

1221131020156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 305282755043 (or 305282755041 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 25.

Adding to 1221131020156 its reverse (6510201311221), we get a palindrome (7731332331377).

The spelling of 1221131020156 in words is "one trillion, two hundred twenty-one billion, one hundred thirty-one million, twenty thousand, one hundred fifty-six".