1213421618 has 4 divisors (see below), whose sum is σ = 1820132430. Its totient is φ = 606710808.

The previous prime is 1213421617. The next prime is 1213421633. The reversal of 1213421618 is 8161243121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8161243121 = 181 ⋅45089741.

It can be written as a sum of positive squares in only one way, i.e., 751472569 + 461949049 = 27413^2 + 21493^2 .

It is not an unprimeable number, because it can be changed into a prime (1213421617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 303355403 + ... + 303355406.

Almost surely, 2^1213421618 is an apocalyptic number.

1213421618 is a deficient number, since it is larger than the sum of its proper divisors (606710812).

1213421618 is an equidigital number, since it uses as much as digits as its factorization.

1213421618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 606710811.

The product of its digits is 2304, while the sum is 29.

The square root of 1213421618 is about 34834.2018424421. The cubic root of 1213421618 is about 1066.6057222775.

Adding to 1213421618 its reverse (8161243121), we get a palindrome (9374664739).

The spelling of 1213421618 in words is "one billion, two hundred thirteen million, four hundred twenty-one thousand, six hundred eighteen".