991492945 has 4 divisors (see below), whose sum is σ = 1189791540. Its totient is φ = 793194352.

The previous prime is 991492939. The next prime is 991492949. The reversal of 991492945 is 549294199.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 549294199 = 19 ⋅28910221.

It can be written as a sum of positive squares in 2 ways, for example, as 379821121 + 611671824 = 19489^2 + 24732^2 .

It is a cyclic number.

It is not a de Polignac number, because 991492945 - 2⁹ = 991492433 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 991492892 and 991492901.

It is not an unprimeable number, because it can be changed into a prime (991492949) 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, 99149290 + ... + 99149299.

It is an arithmetic number, because the mean of its divisors is an integer number (297447885).

Almost surely, 2^991492945 is an apocalyptic number.

It is an amenable number.

991492945 is a deficient number, since it is larger than the sum of its proper divisors (198298595).

991492945 is a wasteful number, since it uses less digits than its factorization.

991492945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198298594.

The product of its digits is 1049760, while the sum is 52.

The square root of 991492945 is about 31487.9809609953. The cubic root of 991492945 is about 997.1562356703.

The spelling of 991492945 in words is "nine hundred ninety-one million, four hundred ninety-two thousand, nine hundred forty-five".