1661601 has 4 divisors (see below), whose sum is σ = 2215472. Its totient is φ = 1107732.

The previous prime is 1661599. The next prime is 1661623. The reversal of 1661601 is 1061661.

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 not a de Polignac number, because 1661601 - 2¹ = 1661599 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 276931 + ... + 276936.

It is an arithmetic number, because the mean of its divisors is an integer number (553868).

2^1661601 is an apocalyptic number.

It is an amenable number.

1661601 is a deficient number, since it is larger than the sum of its proper divisors (553871).

1661601 is an equidigital number, since it uses as much as digits as its factorization.

1661601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 553870.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 1661601 is about 1289.0310314341. The cubic root of 1661601 is about 118.4428680069.

The spelling of 1661601 in words is "one million, six hundred sixty-one thousand, six hundred one".