1213611778 has 12 divisors (see below), whose sum is σ = 1885357890. Its totient is φ = 585880736.

The previous prime is 1213611761. The next prime is 1213611799. The reversal of 1213611778 is 8771163121.

It can be written as a sum of positive squares in 3 ways, for example, as 975125529 + 238486249 = 31227^2 + 15443^2 .

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 359083 + ... + 362446.

Almost surely, 2^1213611778 is an apocalyptic number.

1213611778 is a deficient number, since it is larger than the sum of its proper divisors (671746112).

1213611778 is an equidigital number, since it uses as much as digits as its factorization.

1213611778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721589 (or 721560 counting only the distinct ones).

The product of its digits is 14112, while the sum is 37.

The square root of 1213611778 is about 34836.9312368354. The cubic root of 1213611778 is about 1066.6614366714.

Adding to 1213611778 its reverse (8771163121), we get a palindrome (9984774899).

The spelling of 1213611778 in words is "one billion, two hundred thirteen million, six hundred eleven thousand, seven hundred seventy-eight".