1243511012021 has 4 divisors (see below), whose sum is σ = 1243827511500. Its totient is φ = 1243194512544.

The previous prime is 1243511011997. The next prime is 1243511012063. The reversal of 1243511012021 is 1202101153421.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 848858182225 + 394652829796 = 921335^2 + 628214^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243511012021 - 2¹⁴ = 1243510995637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243511014021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 158243846 + ... + 158251703.

It is an arithmetic number, because the mean of its divisors is an integer number (310956877875).

Almost surely, 2^{1243511012021} is an apocalyptic number.

It is an amenable number.

1243511012021 is a deficient number, since it is larger than the sum of its proper divisors (316499479).

1243511012021 is an equidigital number, since it uses as much as digits as its factorization.

1243511012021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316499478.

The product of its (nonzero) digits is 480, while the sum is 23.

Adding to 1243511012021 its reverse (1202101153421), we get a palindrome (2445612165442).

The spelling of 1243511012021 in words is "one trillion, two hundred forty-three billion, five hundred eleven million, twelve thousand, twenty-one".