1691990 has 8 divisors (see below), whose sum is σ = 3045600. Its totient is φ = 676792.

The previous prime is 1691983. The next prime is 1692013. The reversal of 1691990 is 991961.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 1691990.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 84590 + ... + 84609.

It is an arithmetic number, because the mean of its divisors is an integer number (380700).

2^1691990 is an apocalyptic number.

1691990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1691990 is a deficient number, since it is larger than the sum of its proper divisors (1353610).

1691990 is a wasteful number, since it uses less digits than its factorization.

1691990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169206.

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

The square root of 1691990 is about 1300.7651594350. The cubic root of 1691990 is about 119.1605769515.

The spelling of 1691990 in words is "one million, six hundred ninety-one thousand, nine hundred ninety".