1061991 has 20 divisors (see below), whose sum is σ = 1814032. Its totient is φ = 606528.

The previous prime is 1061969. The next prime is 1061993. The reversal of 1061991 is 1991601.

It is not a de Polignac number, because 1061991 - 2⁵ = 1061959 is a prime.

It is a super-2 number, since 2×1061991² = 2255649768162, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

1061991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1061993) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 370 + ... + 1503.

2^1061991 is an apocalyptic number.

1061991 is a deficient number, since it is larger than the sum of its proper divisors (752041).

1061991 is an equidigital number, since it uses as much as digits as its factorization.

1061991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1892 (or 1883 counting only the distinct ones).

The product of its (nonzero) digits is 486, while the sum is 27.

The square root of 1061991 is about 1030.5294755610. The cubic root of 1061991 is about 102.0250803378.

It can be divided in two parts, 10 and 61991, that added together give a square (62001 = 249²).

The spelling of 1061991 in words is "one million, sixty-one thousand, nine hundred ninety-one".