1871887038661 has 2 divisors, whose sum is σ = 1871887038662. Its totient is φ = 1871887038660.

The previous prime is 1871887038649. The next prime is 1871887038733. The reversal of 1871887038661 is 1668307881781.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1598216810436 + 273670228225 = 1264206^2 + 523135^2 .

It is a cyclic number.

It is not a de Polignac number, because 1871887038661 - 2⁷ = 1871887038533 is a prime.

It is a super-2 number, since 2×1871887038661² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1871887038593 and 1871887038602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1871887038631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 935943519330 + 935943519331.

It is an arithmetic number, because the mean of its divisors is an integer number (935943519331).

Almost surely, 2^{1871887038661} is an apocalyptic number.

It is an amenable number.

1871887038661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1871887038661 is an equidigital number, since it uses as much as digits as its factorization.

1871887038661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21676032, while the sum is 64.

The spelling of 1871887038661 in words is "one trillion, eight hundred seventy-one billion, eight hundred eighty-seven million, thirty-eight thousand, six hundred sixty-one".