1661985 has 32 divisors (see below), whose sum is σ = 3185280. Its totient is φ = 817344.

The previous prime is 1661983. The next prime is 1662007. The reversal of 1661985 is 5891661.

It is not a de Polignac number, because 1661985 - 2¹ = 1661983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661983) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1282 + ... + 2228.

It is an arithmetic number, because the mean of its divisors is an integer number (99540).

2^1661985 is an apocalyptic number.

1661985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661985 is a deficient number, since it is larger than the sum of its proper divisors (1523295).

1661985 is a wasteful number, since it uses less digits than its factorization.

1661985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 974 (or 968 counting only the distinct ones).

The product of its digits is 12960, while the sum is 36.

The square root of 1661985 is about 1289.1799719201. The cubic root of 1661985 is about 118.4519914483.

It can be divided in two parts, 16 and 61985, that added together give a square (62001 = 249²).

The spelling of 1661985 in words is "one million, six hundred sixty-one thousand, nine hundred eighty-five".