1211217817 has 2 divisors, whose sum is σ = 1211217818. Its totient is φ = 1211217816.

The previous prime is 1211217797. The next prime is 1211217827. The reversal of 1211217817 is 7187121121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1010031961 + 201185856 = 31781^2 + 14184^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211217817 - 2¹⁵ = 1211185049 is a prime.

It is not a weakly prime, because it can be changed into another prime (1211217827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605608908 + 605608909.

It is an arithmetic number, because the mean of its divisors is an integer number (605608909).

Almost surely, 2^1211217817 is an apocalyptic number.

It is an amenable number.

1211217817 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211217817 is an equidigital number, since it uses as much as digits as its factorization.

1211217817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1568, while the sum is 31.

The square root of 1211217817 is about 34802.5547481790. The cubic root of 1211217817 is about 1065.9596123585.

Adding to 1211217817 its reverse (7187121121), we get a palindrome (8398338938).

It can be divided in two parts, 12112 and 17817, that added together give a square (29929 = 173²).

The spelling of 1211217817 in words is "one billion, two hundred eleven million, two hundred seventeen thousand, eight hundred seventeen".