1221023213543 has 16 divisors (see below), whose sum is σ = 1418425559040. Its totient is φ = 1029441617856.

The previous prime is 1221023213513. The next prime is 1221023213581. The reversal of 1221023213543 is 3453123201221.

It is a cyclic number.

It is not a de Polignac number, because 1221023213543 - 2²² = 1221019019239 is a prime.

It is a super-2 number, since 2×1221023213543² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221023213513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3067883 + ... + 3442956.

It is an arithmetic number, because the mean of its divisors is an integer number (88651597440).

Almost surely, 2^{1221023213543} is an apocalyptic number.

1221023213543 is a deficient number, since it is larger than the sum of its proper divisors (197402345497).

1221023213543 is an equidigital number, since it uses as much as digits as its factorization.

1221023213543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6511286.

The product of its (nonzero) digits is 8640, while the sum is 29.

Adding to 1221023213543 its reverse (3453123201221), we get a palindrome (4674146414764).

The spelling of 1221023213543 in words is "one trillion, two hundred twenty-one billion, twenty-three million, two hundred thirteen thousand, five hundred forty-three".