1605561 has 8 divisors (see below), whose sum is σ = 2233920. Its totient is φ = 1023792.

The previous prime is 1605559. The next prime is 1605563. The reversal of 1605561 is 1655061.

It is an interprime number because it is at equal distance from previous prime (1605559) and next prime (1605563).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1605561 - 2¹ = 1605559 is a prime.

It is a super-2 number, since 2×1605561² = 5155652249442, which contains 22 as substring.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1605563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11566 + ... + 11703.

It is an arithmetic number, because the mean of its divisors is an integer number (279240).

2^1605561 is an apocalyptic number.

It is an amenable number.

1605561 is a deficient number, since it is larger than the sum of its proper divisors (628359).

1605561 is a wasteful number, since it uses less digits than its factorization.

1605561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23295.

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 1605561 is about 1267.1073356271. The cubic root of 1605561 is about 117.0960566994.

The spelling of 1605561 in words is "one million, six hundred five thousand, five hundred sixty-one".