1906991 has 4 divisors (see below), whose sum is σ = 1910232. Its totient is φ = 1903752.

The previous prime is 1906987. The next prime is 1906997. The reversal of 1906991 is 1996091.

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 1906991 - 2² = 1906987 is a prime.

It is a super-2 number, since 2×1906991² = 7273229348162, 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 (1906997) 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, 461 + ... + 2006.

It is an arithmetic number, because the mean of its divisors is an integer number (477558).

2^1906991 is an apocalyptic number.

1906991 is a deficient number, since it is larger than the sum of its proper divisors (3241).

1906991 is an equidigital number, since it uses as much as digits as its factorization.

1906991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3240.

The product of its (nonzero) digits is 4374, while the sum is 35.

The square root of 1906991 is about 1380.9384490266. The cubic root of 1906991 is about 124.0079556117.

The spelling of 1906991 in words is "one million, nine hundred six thousand, nine hundred ninety-one".