1664685 has 64 divisors (see below), whose sum is σ = 3456000. Its totient is φ = 751680.

The previous prime is 1664681. The next prime is 1664701. The reversal of 1664685 is 5864661.

1664685 is a `hidden beast` number, since 1 + 6 + 646 + 8 + 5 = 666.

It is not a de Polignac number, because 1664685 - 2² = 1664681 is a prime.

It is a super-2 number, since 2×1664685² = 5542352298450, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664681) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 28186 + ... + 28244.

It is an arithmetic number, because the mean of its divisors is an integer number (54000).

2^1664685 is an apocalyptic number.

1664685 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1664685 is an abundant number, since it is smaller than the sum of its proper divisors (1791315).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1664685 is a wasteful number, since it uses less digits than its factorization.

1664685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 97 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 1664685 is about 1290.2267242621. The cubic root of 1664685 is about 118.5161010008.

It can be divided in two parts, 166 and 4685, that added together give a triangular number (4851 = T₉₈).

The spelling of 1664685 in words is "one million, six hundred sixty-four thousand, six hundred eighty-five".