1056105991 has 4 divisors (see below), whose sum is σ = 1058984032. Its totient is φ = 1053227952.

The previous prime is 1056105983. The next prime is 1056106033. The reversal of 1056105991 is 1995016501.

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 1056105991 - 2³ = 1056105983 is a prime.

It is a super-2 number, since 2×1056105991² = 2230719728452184162, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1056105991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1056105961) 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, 1438470 + ... + 1439203.

It is an arithmetic number, because the mean of its divisors is an integer number (264746008).

Almost surely, 2^1056105991 is an apocalyptic number.

1056105991 is a deficient number, since it is larger than the sum of its proper divisors (2878041).

1056105991 is an equidigital number, since it uses as much as digits as its factorization.

1056105991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2878040.

The product of its (nonzero) digits is 12150, while the sum is 37.

The square root of 1056105991 is about 32497.7844014019. The cubic root of 1056105991 is about 1018.3627427651.

The spelling of 1056105991 in words is "one billion, fifty-six million, one hundred five thousand, nine hundred ninety-one".