1664099 has 4 divisors (see below), whose sum is σ = 1666680. Its totient is φ = 1661520.

The previous prime is 1664083. The next prime is 1664101. The reversal of 1664099 is 9904661.

It is a Cunningham number, because it is equal to 1290²-1.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9904661 = 13 ⋅761897.

It is a cyclic number.

It is not a de Polignac number, because 1664099 - 2⁴ = 1664083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664009) 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, 644 + ... + 1934.

It is an arithmetic number, because the mean of its divisors is an integer number (416670).

2^1664099 is an apocalyptic number.

1664099 is a deficient number, since it is larger than the sum of its proper divisors (2581).

1664099 is a wasteful number, since it uses less digits than its factorization.

1664099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2580.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 1664099 is about 1289.9996124030. Note that the first 3 decimals coincide. The cubic root of 1664099 is about 118.5021927467.

The spelling of 1664099 in words is "one million, six hundred sixty-four thousand, ninety-nine".