1217938681 has 4 divisors (see below), whose sum is σ = 1218385764. Its totient is φ = 1217491600.

The previous prime is 1217938679. The next prime is 1217938691. The reversal of 1217938681 is 1868397121.

It is a happy number.

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 866713600 + 351225081 = 29440^2 + 18741^2 .

It is a cyclic number.

It is not a de Polignac number, because 1217938681 - 2¹ = 1217938679 is a prime.

It is a super-2 number, since 2×1217938681² = 2966749261352039522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1217938651) 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, 219430 + ... + 224911.

It is an arithmetic number, because the mean of its divisors is an integer number (304596441).

Almost surely, 2^1217938681 is an apocalyptic number.

It is an amenable number.

1217938681 is a deficient number, since it is larger than the sum of its proper divisors (447083).

1217938681 is an equidigital number, since it uses as much as digits as its factorization.

1217938681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 447082.

The product of its digits is 145152, while the sum is 46.

The square root of 1217938681 is about 34898.9782228649. The cubic root of 1217938681 is about 1067.9275929089.

The spelling of 1217938681 in words is "one billion, two hundred seventeen million, nine hundred thirty-eight thousand, six hundred eighty-one".