891668731 has 2 divisors, whose sum is σ = 891668732. Its totient is φ = 891668730.

The previous prime is 891668633. The next prime is 891668753. The reversal of 891668731 is 137866198.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 891668731 - 2¹⁷ = 891537659 is a prime.

It is a super-2 number, since 2×891668731² = 1590146251686300722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (891668231) 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, 445834365 + 445834366.

It is an arithmetic number, because the mean of its divisors is an integer number (445834366).

Almost surely, 2^891668731 is an apocalyptic number.

891668731 is a deficient number, since it is larger than the sum of its proper divisors (1).

891668731 is an equidigital number, since it uses as much as digits as its factorization.

891668731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 49.

The square root of 891668731 is about 29860.8226778835. The cubic root of 891668731 is about 962.5009770272.

The spelling of 891668731 in words is "eight hundred ninety-one million, six hundred sixty-eight thousand, seven hundred thirty-one".