1605681 has 36 divisors (see below), whose sum is σ = 2952144. Its totient is φ = 831600.

The previous prime is 1605677. The next prime is 1605691. The reversal of 1605681 is 1865061.

It is not a de Polignac number, because 1605681 - 2² = 1605677 is a prime.

It is a super-2 number, since 2×1605681² = 5156422947522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1605631) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4686 + ... + 5016.

It is an arithmetic number, because the mean of its divisors is an integer number (82004).

2^1605681 is an apocalyptic number.

1605681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1605681 is a deficient number, since it is larger than the sum of its proper divisors (1346463).

1605681 is a wasteful number, since it uses less digits than its factorization.

1605681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362 (or 352 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 1605681 is about 1267.1546866898. The cubic root of 1605681 is about 117.0989738889.

The spelling of 1605681 in words is "one million, six hundred five thousand, six hundred eighty-one".