2109670781 has 2 divisors, whose sum is σ = 2109670782. Its totient is φ = 2109670780.

The previous prime is 2109670733. The next prime is 2109670799. The reversal of 2109670781 is 1870769012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2085748900 + 23921881 = 45670^2 + 4891^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2109670781 is a prime.

It is a super-2 number, since 2×2109670781² = 8901421608410299922, which contains 22 as substring.

It is a Sophie Germain prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2109670711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1054835390 + 1054835391.

It is an arithmetic number, because the mean of its divisors is an integer number (1054835391).

Almost surely, 2^2109670781 is an apocalyptic number.

It is an amenable number.

2109670781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2109670781 is an equidigital number, since it uses as much as digits as its factorization.

2109670781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 42336, while the sum is 41.

The square root of 2109670781 is about 45931.1526199811. The cubic root of 2109670781 is about 1282.5419013120.

The spelling of 2109670781 in words is "two billion, one hundred nine million, six hundred seventy thousand, seven hundred eighty-one".