1663965 has 24 divisors (see below), whose sum is σ = 2920320. Its totient is φ = 876384.

The previous prime is 1663951. The next prime is 1663967. The reversal of 1663965 is 5693661.

1663965 is a `hidden beast` number, since 16 + 639 + 6 + 5 = 666.

It is not a de Polignac number, because 1663965 - 2⁸ = 1663709 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1663967) 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 23 ways as a sum of consecutive naturals, for example, 4456 + ... + 4814.

It is an arithmetic number, because the mean of its divisors is an integer number (121680).

2^1663965 is an apocalyptic number.

1663965 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1663965 is a deficient number, since it is larger than the sum of its proper divisors (1256355).

1663965 is a wasteful number, since it uses less digits than its factorization.

1663965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473 (or 470 counting only the distinct ones).

The product of its digits is 29160, while the sum is 36.

The square root of 1663965 is about 1289.9476733573. The cubic root of 1663965 is about 118.4990119022.

It can be divided in two parts, 1663 and 965, that added together give a triangular number (2628 = T₇₂).

The spelling of 1663965 in words is "one million, six hundred sixty-three thousand, nine hundred sixty-five".