1221421345 has 4 divisors (see below), whose sum is σ = 1465705620. Its totient is φ = 977137072.

The previous prime is 1221421343. The next prime is 1221421367. The reversal of 1221421345 is 5431241221.

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 765684241 + 455737104 = 27671^2 + 21348^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221421345 - 2¹ = 1221421343 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221421343) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122142130 + ... + 122142139.

It is an arithmetic number, because the mean of its divisors is an integer number (366426405).

Almost surely, 2^1221421345 is an apocalyptic number.

It is an amenable number.

1221421345 is a deficient number, since it is larger than the sum of its proper divisors (244284275).

1221421345 is an equidigital number, since it uses as much as digits as its factorization.

1221421345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244284274.

The product of its digits is 1920, while the sum is 25.

The square root of 1221421345 is about 34948.8389649785. The cubic root of 1221421345 is about 1068.9445279552.

Adding to 1221421345 its reverse (5431241221), we get a palindrome (6652662566).

The spelling of 1221421345 in words is "one billion, two hundred twenty-one million, four hundred twenty-one thousand, three hundred forty-five".