1690861 has 4 divisors (see below), whose sum is σ = 1693692. Its totient is φ = 1688032.

The previous prime is 1690853. The next prime is 1690883. The reversal of 1690861 is 1680961.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1020100 + 670761 = 1010^2 + 819^2 .

It is a cyclic number.

It is not a de Polignac number, because 1690861 - 2³ = 1690853 is a prime.

It is a Duffinian number.

1690861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1690811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130 + ... + 1843.

It is an arithmetic number, because the mean of its divisors is an integer number (423423).

2^1690861 is an apocalyptic number.

It is an amenable number.

1690861 is a deficient number, since it is larger than the sum of its proper divisors (2831).

1690861 is an equidigital number, since it uses as much as digits as its factorization.

1690861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2830.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1690861 is about 1300.3311116789. The cubic root of 1690861 is about 119.1340672942.

The spelling of 1690861 in words is "one million, six hundred ninety thousand, eight hundred sixty-one".