1057991 has 4 divisors (see below), whose sum is σ = 1154184. Its totient is φ = 961800.

The previous prime is 1057981. The next prime is 1057993. The reversal of 1057991 is 1997501.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1057991 is a prime.

It is a super-2 number, since 2×1057991² = 2238689912162, 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 (1057993) 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, 48080 + ... + 48101.

It is an arithmetic number, because the mean of its divisors is an integer number (288546).

2^1057991 is an apocalyptic number.

1057991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1057991 is a deficient number, since it is larger than the sum of its proper divisors (96193).

1057991 is an equidigital number, since it uses as much as digits as its factorization.

1057991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96192.

The product of its (nonzero) digits is 2835, while the sum is 32.

The square root of 1057991 is about 1028.5868947250. The cubic root of 1057991 is about 101.8968263421.

It can be divided in two parts, 1057 and 991, that added together give a 11-th power (2048 = 2¹¹).

The spelling of 1057991 in words is "one million, fifty-seven thousand, nine hundred ninety-one".