1221131020158 has 48 divisors (see below), whose sum is σ = 3023884936800. Its totient is φ = 348879354048.

The previous prime is 1221131020157. The next prime is 1221131020181. The reversal of 1221131020158 is 8510201311221.

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 polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2864668 + ... + 3263216.

It is an arithmetic number, because the mean of its divisors is an integer number (62997602850).

Almost surely, 2^{1221131020158} is an apocalyptic number.

1221131020158 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1221131020158 is an abundant number, since it is smaller than the sum of its proper divisors (1802753916642).

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

1221131020158 is a wasteful number, since it uses less digits than its factorization.

1221131020158 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422881 (or 422878 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 27.

Adding to 1221131020158 its reverse (8510201311221), we get a palindrome (9731332331379).

The spelling of 1221131020158 in words is "one trillion, two hundred twenty-one billion, one hundred thirty-one million, twenty thousand, one hundred fifty-eight".