999697891 has 2 divisors, whose sum is σ = 999697892. Its totient is φ = 999697890.

The previous prime is 999697883. The next prime is 999697961. The reversal of 999697891 is 198796999.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 999697891 - 2³ = 999697883 is a prime.

It is not a weakly prime, because it can be changed into another prime (999697871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499848945 + 499848946.

It is an arithmetic number, because the mean of its divisors is an integer number (499848946).

Almost surely, 2^999697891 is an apocalyptic number.

999697891 is a deficient number, since it is larger than the sum of its proper divisors (1).

999697891 is an equidigital number, since it uses as much as digits as its factorization.

999697891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19840464, while the sum is 67.

The square root of 999697891 is about 31617.9994781454. Note that the first 3 decimals coincide. The cubic root of 999697891 is about 999.8992868572.

The spelling of 999697891 in words is "nine hundred ninety-nine million, six hundred ninety-seven thousand, eight hundred ninety-one".