991071859 has 2 divisors, whose sum is σ = 991071860. Its totient is φ = 991071858.

The previous prime is 991071821. The next prime is 991071881. The reversal of 991071859 is 958170199.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991071859 is a prime.

It is not a weakly prime, because it can be changed into another prime (991071659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495535929 + 495535930.

It is an arithmetic number, because the mean of its divisors is an integer number (495535930).

Almost surely, 2^991071859 is an apocalyptic number.

991071859 is a deficient number, since it is larger than the sum of its proper divisors (1).

991071859 is an equidigital number, since it uses as much as digits as its factorization.

991071859 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 204120, while the sum is 49.

The square root of 991071859 is about 31481.2937948871. The cubic root of 991071859 is about 997.0150519504.

The spelling of 991071859 in words is "nine hundred ninety-one million, seventy-one thousand, eight hundred fifty-nine".