1221421153 has 4 divisors (see below), whose sum is σ = 1221947028. Its totient is φ = 1220895280.

The previous prime is 1221421121. The next prime is 1221421163. The reversal of 1221421153 is 3511241221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3511241221 = 227 ⋅15468023.

It can be written as a sum of positive squares in 2 ways, for example, as 561547809 + 659873344 = 23697^2 + 25688^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221421153 - 2⁵ = 1221421121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221421163) 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, 259438 + ... + 264103.

It is an arithmetic number, because the mean of its divisors is an integer number (305486757).

Almost surely, 2^1221421153 is an apocalyptic number.

It is an amenable number.

1221421153 is a deficient number, since it is larger than the sum of its proper divisors (525875).

1221421153 is an equidigital number, since it uses as much as digits as its factorization.

1221421153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525874.

The product of its digits is 480, while the sum is 22.

The square root of 1221421153 is about 34948.8362181060. The cubic root of 1221421153 is about 1068.9444719446.

Adding to 1221421153 its reverse (3511241221), we get a palindrome (4732662374).

The spelling of 1221421153 in words is "one billion, two hundred twenty-one million, four hundred twenty-one thousand, one hundred fifty-three".