1906581 has 4 divisors (see below), whose sum is σ = 2542112. Its totient is φ = 1271052.

The previous prime is 1906579. The next prime is 1906589. The reversal of 1906581 is 1856091.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1906581 - 2¹ = 1906579 is a prime.

It is a super-2 number, since 2×1906581² = 7270102219122, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1906589) 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, 317761 + ... + 317766.

It is an arithmetic number, because the mean of its divisors is an integer number (635528).

2^1906581 is an apocalyptic number.

It is an amenable number.

1906581 is a deficient number, since it is larger than the sum of its proper divisors (635531).

1906581 is an equidigital number, since it uses as much as digits as its factorization.

1906581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 635530.

The product of its (nonzero) digits is 2160, while the sum is 30.

The square root of 1906581 is about 1380.7899912731. The cubic root of 1906581 is about 123.9990678043. Note that the first 3 decimals are identical.

The spelling of 1906581 in words is "one million, nine hundred six thousand, five hundred eighty-one".