87109991 has 2 divisors, whose sum is σ = 87109992. Its totient is φ = 87109990.

The previous prime is 87109973. The next prime is 87110017. The reversal of 87109991 is 19990178.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-87109991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87109961) 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, 43554995 + 43554996.

It is an arithmetic number, because the mean of its divisors is an integer number (43554996).

Almost surely, 2^87109991 is an apocalyptic number.

87109991 is a deficient number, since it is larger than the sum of its proper divisors (1).

87109991 is an equidigital number, since it uses as much as digits as its factorization.

87109991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40824, while the sum is 44.

The square root of 87109991 is about 9333.2733271881. The cubic root of 87109991 is about 443.2914173849.

The spelling of 87109991 in words is "eighty-seven million, one hundred nine thousand, nine hundred ninety-one".