1221311240021 has 4 divisors (see below), whose sum is σ = 1221314392044. Its totient is φ = 1221308088000.

The previous prime is 1221311240003. The next prime is 1221311240027. The reversal of 1221311240021 is 1200421131221.

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 352733839396 + 868577400625 = 593914^2 + 931975^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221311240021 - 2¹⁰ = 1221311238997 is a prime.

It is a super-3 number, since 3×1221311240021³ (a number of 37 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221311239975 and 1221311240002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221311240027) 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, 897410 + ... + 1802211.

It is an arithmetic number, because the mean of its divisors is an integer number (305328598011).

Almost surely, 2^{1221311240021} is an apocalyptic number.

It is an amenable number.

1221311240021 is a deficient number, since it is larger than the sum of its proper divisors (3152023).

1221311240021 is an equidigital number, since it uses as much as digits as its factorization.

1221311240021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3152022.

The product of its (nonzero) digits is 192, while the sum is 20.

Adding to 1221311240021 its reverse (1200421131221), we get a palindrome (2421732371242).

The spelling of 1221311240021 in words is "one trillion, two hundred twenty-one billion, three hundred eleven million, two hundred forty thousand, twenty-one".