2117387861 has 2 divisors, whose sum is σ = 2117387862. Its totient is φ = 2117387860.

The previous prime is 2117387837. The next prime is 2117387891. The reversal of 2117387861 is 1687837112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2038071025 + 79316836 = 45145^2 + 8906^2 .

It is a cyclic number.

It is not a de Polignac number, because 2117387861 - 2¹⁰ = 2117386837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2117387821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1058693930 + 1058693931.

It is an arithmetic number, because the mean of its divisors is an integer number (1058693931).

Almost surely, 2^2117387861 is an apocalyptic number.

It is an amenable number.

2117387861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2117387861 is an equidigital number, since it uses as much as digits as its factorization.

2117387861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 112896, while the sum is 44.

The square root of 2117387861 is about 46015.0829728688. The cubic root of 2117387861 is about 1284.1038250704.

The spelling of 2117387861 in words is "two billion, one hundred seventeen million, three hundred eighty-seven thousand, eight hundred sixty-one".