891191687 has 2 divisors, whose sum is σ = 891191688. Its totient is φ = 891191686.

The previous prime is 891191669. The next prime is 891191699. The reversal of 891191687 is 786191198.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 891191687 - 2²⁶ = 824082823 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (891191617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445595843 + 445595844.

It is an arithmetic number, because the mean of its divisors is an integer number (445595844).

Almost surely, 2^891191687 is an apocalyptic number.

891191687 is a deficient number, since it is larger than the sum of its proper divisors (1).

891191687 is an equidigital number, since it uses as much as digits as its factorization.

891191687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 50.

The square root of 891191687 is about 29852.8338185841. The cubic root of 891191687 is about 962.3292999580.

The spelling of 891191687 in words is "eight hundred ninety-one million, one hundred ninety-one thousand, six hundred eighty-seven".