1231355105021 has 4 divisors (see below), whose sum is σ = 1238234184000. Its totient is φ = 1224476026044.

The previous prime is 1231355104957. The next prime is 1231355105047. The reversal of 1231355105021 is 1205015531321.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1231355105021 - 2⁶ = 1231355104957 is a prime.

It is a super-2 number, since 2×1231355105021² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231355105081) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3439539221 + ... + 3439539578.

It is an arithmetic number, because the mean of its divisors is an integer number (309558546000).

Almost surely, 2^{1231355105021} is an apocalyptic number.

It is an amenable number.

1231355105021 is a deficient number, since it is larger than the sum of its proper divisors (6879078979).

1231355105021 is an equidigital number, since it uses as much as digits as its factorization.

1231355105021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6879078978.

The product of its (nonzero) digits is 4500, while the sum is 29.

The spelling of 1231355105021 in words is "one trillion, two hundred thirty-one billion, three hundred fifty-five million, one hundred five thousand, twenty-one".