991793551 has 4 divisors (see below), whose sum is σ = 1133478352. Its totient is φ = 850108752.

The previous prime is 991793503. The next prime is 991793587. The reversal of 991793551 is 155397199.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 991793551 - 2⁷ = 991793423 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991793495 and 991793504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991793951) 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 in 3 ways as a sum of consecutive naturals, for example, 70842390 + ... + 70842403.

It is an arithmetic number, because the mean of its divisors is an integer number (283369588).

Almost surely, 2^991793551 is an apocalyptic number.

991793551 is a deficient number, since it is larger than the sum of its proper divisors (141684801).

991793551 is a wasteful number, since it uses less digits than its factorization.

991793551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141684800.

The product of its digits is 382725, while the sum is 49.

The square root of 991793551 is about 31492.7539443600. The cubic root of 991793551 is about 997.2569998296.

The spelling of 991793551 in words is "nine hundred ninety-one million, seven hundred ninety-three thousand, five hundred fifty-one".