1231221051550 has 24 divisors (see below), whose sum is σ = 2617224178896. Its totient is φ = 422132931840.

The previous prime is 1231221051547. The next prime is 1231221051551. The reversal of 1231221051550 is 551501221321.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231221051551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1758886867 + ... + 1758887566.

It is an arithmetic number, because the mean of its divisors is an integer number (109051007454).

Almost surely, 2^{1231221051550} is an apocalyptic number.

1231221051550 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1231221051550 is an abundant number, since it is smaller than the sum of its proper divisors (1386003127346).

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

1231221051550 is a wasteful number, since it uses less digits than its factorization.

1231221051550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3517774452 (or 3517774447 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 28.

Adding to 1231221051550 its reverse (551501221321), we get a palindrome (1782722272871).

The spelling of 1231221051550 in words is "one trillion, two hundred thirty-one billion, two hundred twenty-one million, fifty-one thousand, five hundred fifty".