1097439991 has 4 divisors (see below), whose sum is σ = 1098712512. Its totient is φ = 1096167472.

The previous prime is 1097439983. The next prime is 1097440033. The reversal of 1097439991 is 1999347901.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1999347901 = 181 ⋅11046121.

It is a cyclic number.

It is not a de Polignac number, because 1097439991 - 2³ = 1097439983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1097409991) 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, 634966 + ... + 636691.

It is an arithmetic number, because the mean of its divisors is an integer number (274678128).

Almost surely, 2^1097439991 is an apocalyptic number.

1097439991 is a deficient number, since it is larger than the sum of its proper divisors (1272521).

1097439991 is an equidigital number, since it uses as much as digits as its factorization.

1097439991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1272520.

The product of its (nonzero) digits is 551124, while the sum is 52.

The square root of 1097439991 is about 33127.6318350709. The cubic root of 1097439991 is about 1031.4786914864.

The spelling of 1097439991 in words is "one billion, ninety-seven million, four hundred thirty-nine thousand, nine hundred ninety-one".