1221001321 has 4 divisors (see below), whose sum is σ = 1224978832. Its totient is φ = 1217023812.

The previous prime is 1221001277. The next prime is 1221001337. The reversal of 1221001321 is 1231001221.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1231001221 = 127 ⋅9692923.

It is a cyclic number.

It is not a de Polignac number, because 1221001321 - 2²⁹ = 684130409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221031321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1988295 + ... + 1988908.

It is an arithmetic number, because the mean of its divisors is an integer number (306244708).

Almost surely, 2^1221001321 is an apocalyptic number.

It is an amenable number.

1221001321 is a deficient number, since it is larger than the sum of its proper divisors (3977511).

1221001321 is an equidigital number, since it uses as much as digits as its factorization.

1221001321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3977510.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 1221001321 is about 34942.8293216219. The cubic root of 1221001321 is about 1068.8219838843.

Adding to 1221001321 its reverse (1231001221), we get a palindrome (2452002542).

The spelling of 1221001321 in words is "one billion, two hundred twenty-one million, one thousand, three hundred twenty-one".