2156661887 has 2 divisors, whose sum is σ = 2156661888. Its totient is φ = 2156661886.

The previous prime is 2156661863. The next prime is 2156661889. The reversal of 2156661887 is 7881666512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2156661887 - 2²⁶ = 2089553023 is a prime.

Together with 2156661889, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2156661889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1078330943 + 1078330944.

It is an arithmetic number, because the mean of its divisors is an integer number (1078330944).

Almost surely, 2^2156661887 is an apocalyptic number.

2156661887 is a deficient number, since it is larger than the sum of its proper divisors (1).

2156661887 is an equidigital number, since it uses as much as digits as its factorization.

2156661887 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 967680, while the sum is 50.

The square root of 2156661887 is about 46439.8738908710. The cubic root of 2156661887 is about 1291.9945682420.

The spelling of 2156661887 in words is "two billion, one hundred fifty-six million, six hundred sixty-one thousand, eight hundred eighty-seven".