2061991 has 4 divisors (see below), whose sum is σ = 2097000. Its totient is φ = 2026984.

The previous prime is 2061971. The next prime is 2062001. The reversal of 2061991 is 1991602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1991602 = 2 ⋅995801.

It is a cyclic number.

It is not a de Polignac number, because 2061991 - 2¹¹ = 2059943 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 (2061971) 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, 17416 + ... + 17533.

It is an arithmetic number, because the mean of its divisors is an integer number (524250).

2^2061991 is an apocalyptic number.

2061991 is a deficient number, since it is larger than the sum of its proper divisors (35009).

2061991 is an equidigital number, since it uses as much as digits as its factorization.

2061991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35008.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 2061991 is about 1435.9634396460. The cubic root of 2061991 is about 127.2806120811.

It can be divided in two parts, 206 and 1991, that added together give a cube (2197 = 13³).

The spelling of 2061991 in words is "two million, sixty-one thousand, nine hundred ninety-one".