1665261 has 24 divisors (see below), whose sum is σ = 2658656. Its totient is φ = 997920.

The previous prime is 1665247. The next prime is 1665263. The reversal of 1665261 is 1625661.

It is a happy number.

1665261 is a `hidden beast` number, since 1 + 6 + 652 + 6 + 1 = 666.

It is not a de Polignac number, because 1665261 - 2⁶ = 1665197 is a prime.

1665261 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665263) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4866 + ... + 5196.

2^1665261 is an apocalyptic number.

It is an amenable number.

1665261 is a deficient number, since it is larger than the sum of its proper divisors (993395).

1665261 is a wasteful number, since it uses less digits than its factorization.

1665261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393 (or 390 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 1665261 is about 1290.4499215390. The cubic root of 1665261 is about 118.5297687322.

The spelling of 1665261 in words is "one million, six hundred sixty-five thousand, two hundred sixty-one".