991900943 has 4 divisors (see below), whose sum is σ = 1082073768. Its totient is φ = 901728120.

The previous prime is 991900939. The next prime is 991900993. The reversal of 991900943 is 349009199.

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 991900943 - 2² = 991900939 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991900894 and 991900903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991900993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45086396 + ... + 45086417.

It is an arithmetic number, because the mean of its divisors is an integer number (270518442).

Almost surely, 2^991900943 is an apocalyptic number.

991900943 is a deficient number, since it is larger than the sum of its proper divisors (90172825).

991900943 is a wasteful number, since it uses less digits than its factorization.

991900943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90172824.

The product of its (nonzero) digits is 78732, while the sum is 44.

The square root of 991900943 is about 31494.4589253411. The cubic root of 991900943 is about 997.2929930590.

The spelling of 991900943 in words is "nine hundred ninety-one million, nine hundred thousand, nine hundred forty-three".