1646399 has 4 divisors (see below), whose sum is σ = 1743264. Its totient is φ = 1549536.

The previous prime is 1646387. The next prime is 1646413. The reversal of 1646399 is 9936461.

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 1646399 - 2⁴ = 1646383 is a prime.

It is a super-3 number, since 3×1646399³ = 13388333920350177597, which contains 333 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 (1646299) 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, 48407 + ... + 48440.

It is an arithmetic number, because the mean of its divisors is an integer number (435816).

2^1646399 is an apocalyptic number.

1646399 is a deficient number, since it is larger than the sum of its proper divisors (96865).

1646399 is an equidigital number, since it uses as much as digits as its factorization.

1646399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96864.

The product of its digits is 34992, while the sum is 38.

The square root of 1646399 is about 1283.1208049128. The cubic root of 1646399 is about 118.0805492354.

The spelling of 1646399 in words is "one million, six hundred forty-six thousand, three hundred ninety-nine".