2175778861 has 2 divisors, whose sum is σ = 2175778862. Its totient is φ = 2175778860.

The previous prime is 2175778841. The next prime is 2175778879. The reversal of 2175778861 is 1688775712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1884428100 + 291350761 = 43410^2 + 17069^2 .

It is a cyclic number.

It is not a de Polignac number, because 2175778861 - 2⁷ = 2175778733 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2175778799 and 2175778808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2175778811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1087889430 + 1087889431.

It is an arithmetic number, because the mean of its divisors is an integer number (1087889431).

Almost surely, 2^2175778861 is an apocalyptic number.

It is an amenable number.

2175778861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2175778861 is an equidigital number, since it uses as much as digits as its factorization.

2175778861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1317120, while the sum is 52.

The square root of 2175778861 is about 46645.2447844365. The cubic root of 2175778861 is about 1295.8008216884.

The spelling of 2175778861 in words is "two billion, one hundred seventy-five million, seven hundred seventy-eight thousand, eight hundred sixty-one".