1005609991 has 4 divisors (see below), whose sum is σ = 1019773584. Its totient is φ = 991446400.

The previous prime is 1005609977. The next prime is 1005610009. The reversal of 1005609991 is 1999065001.

1005609991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1999065001 = 2129 ⋅938969.

It is a cyclic number.

It is not a de Polignac number, because 1005609991 - 2¹⁹ = 1005085703 is a prime.

It is a super-2 number, since 2×1005609991² = 2022502907998040162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1005609971) 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, 7081690 + ... + 7081831.

It is an arithmetic number, because the mean of its divisors is an integer number (254943396).

Almost surely, 2^1005609991 is an apocalyptic number.

1005609991 is a deficient number, since it is larger than the sum of its proper divisors (14163593).

1005609991 is an equidigital number, since it uses as much as digits as its factorization.

1005609991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14163592.

The product of its (nonzero) digits is 21870, while the sum is 40.

The square root of 1005609991 is about 31711.3542914837. The cubic root of 1005609991 is about 1001.8665109692.

The spelling of 1005609991 in words is "one billion, five million, six hundred nine thousand, nine hundred ninety-one".