1871685121 has 2 divisors, whose sum is σ = 1871685122. Its totient is φ = 1871685120.

The previous prime is 1871685113. The next prime is 1871685139. The reversal of 1871685121 is 1215861781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1005207025 + 866478096 = 31705^2 + 29436^2 .

It is an emirp because it is prime and its reverse (1215861781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1871685121 - 2³ = 1871685113 is a prime.

It is not a weakly prime, because it can be changed into another prime (1871685521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 935842560 + 935842561.

It is an arithmetic number, because the mean of its divisors is an integer number (935842561).

Almost surely, 2^1871685121 is an apocalyptic number.

It is an amenable number.

1871685121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1871685121 is an equidigital number, since it uses as much as digits as its factorization.

1871685121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26880, while the sum is 40.

The square root of 1871685121 is about 43262.9763308074. The cubic root of 1871685121 is about 1232.3789245349.

The spelling of 1871685121 in words is "one billion, eight hundred seventy-one million, six hundred eighty-five thousand, one hundred twenty-one".