1661399 has 8 divisors (see below), whose sum is σ = 1707888. Its totient is φ = 1615680.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661399 is 9931661.

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

It is a cyclic number.

It is not a de Polignac number, because 1661399 - 2¹² = 1657303 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 (1661599) 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 7 ways as a sum of consecutive naturals, for example, 9089 + ... + 9269.

It is an arithmetic number, because the mean of its divisors is an integer number (213486).

2^1661399 is an apocalyptic number.

1661399 is a deficient number, since it is larger than the sum of its proper divisors (46489).

1661399 is a wasteful number, since it uses less digits than its factorization.

1661399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385.

The product of its digits is 8748, while the sum is 35.

The square root of 1661399 is about 1288.9526756247. The cubic root of 1661399 is about 118.4380681324.

The spelling of 1661399 in words is "one million, six hundred sixty-one thousand, three hundred ninety-nine".