1664667 has 12 divisors (see below), whose sum is σ = 2470000. Its totient is φ = 1079568.

The previous prime is 1664653. The next prime is 1664681. The reversal of 1664667 is 7664661.

1664667 is a `hidden beast` number, since 1 + 6 + 646 + 6 + 7 = 666.

It is an interprime number because it is at equal distance from previous prime (1664653) and next prime (1664681).

It is not a de Polignac number, because 1664667 - 2⁴ = 1664651 is a prime.

It is a super-2 number, since 2×1664667² = 5542232441778, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664627) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2167 + ... + 2832.

2^1664667 is an apocalyptic number.

1664667 is a deficient number, since it is larger than the sum of its proper divisors (805333).

1664667 is a wasteful number, since it uses less digits than its factorization.

1664667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5042 (or 5039 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 1664667 is about 1290.2197487250. The cubic root of 1664667 is about 118.5156738334.

The spelling of 1664667 in words is "one million, six hundred sixty-four thousand, six hundred sixty-seven".