991939151 has 4 divisors (see below), whose sum is σ = 1133644752. Its totient is φ = 850233552.

The previous prime is 991939141. The next prime is 991939159. The reversal of 991939151 is 151939199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 151939199 = 79 ⋅1923281.

It is a de Polignac number, because none of the positive numbers 2^k-991939151 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991939096 and 991939105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991939159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70852790 + ... + 70852803.

It is an arithmetic number, because the mean of its divisors is an integer number (283411188).

Almost surely, 2^991939151 is an apocalyptic number.

991939151 is a deficient number, since it is larger than the sum of its proper divisors (141705601).

991939151 is a wasteful number, since it uses less digits than its factorization.

991939151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141705600.

The product of its digits is 98415, while the sum is 47.

The square root of 991939151 is about 31495.0655023926. The cubic root of 991939151 is about 997.3057981284.

The spelling of 991939151 in words is "nine hundred ninety-one million, nine hundred thirty-nine thousand, one hundred fifty-one".