1405661 has 4 divisors (see below), whose sum is σ = 1410912. Its totient is φ = 1400412.

The previous prime is 1405643. The next prime is 1405669. The reversal of 1405661 is 1665041.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1405661 - 2⁶ = 1405597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1405669) 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 3 ways as a sum of consecutive naturals, for example, 2201 + ... + 2766.

It is an arithmetic number, because the mean of its divisors is an integer number (352728).

2^1405661 is an apocalyptic number.

It is an amenable number.

1405661 is a deficient number, since it is larger than the sum of its proper divisors (5251).

1405661 is an equidigital number, since it uses as much as digits as its factorization.

1405661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5250.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 1405661 is about 1185.6057523477. The cubic root of 1405661 is about 112.0194747173.

The spelling of 1405661 in words is "one million, four hundred five thousand, six hundred sixty-one".