1871556961 has 2 divisors, whose sum is σ = 1871556962. Its totient is φ = 1871556960.

The previous prime is 1871556949. The next prime is 1871556997. The reversal of 1871556961 is 1696551781.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1372257936 + 499299025 = 37044^2 + 22345^2 .

It is a cyclic number.

It is not a de Polignac number, because 1871556961 - 2¹⁹ = 1871032673 is a prime.

It is not a weakly prime, because it can be changed into another prime (1871556901) 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, 935778480 + 935778481.

It is an arithmetic number, because the mean of its divisors is an integer number (935778481).

Almost surely, 2^1871556961 is an apocalyptic number.

It is an amenable number.

1871556961 is a deficient number, since it is larger than the sum of its proper divisors (1).

1871556961 is an equidigital number, since it uses as much as digits as its factorization.

1871556961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 453600, while the sum is 49.

The square root of 1871556961 is about 43261.4951313521. The cubic root of 1871556961 is about 1232.3507956425.

The spelling of 1871556961 in words is "one billion, eight hundred seventy-one million, five hundred fifty-six thousand, nine hundred sixty-one".