1653661 has 4 divisors (see below), whose sum is σ = 1677024. Its totient is φ = 1630300.

The previous prime is 1653643. The next prime is 1653671. The reversal of 1653661 is 1663561.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1663561 = 257 ⋅6473.

It is a cyclic number.

It is not a de Polignac number, because 1653661 - 2⁹ = 1653149 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 (1653611) 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, 11575 + ... + 11716.

It is an arithmetic number, because the mean of its divisors is an integer number (419256).

2^1653661 is an apocalyptic number.

It is an amenable number.

1653661 is a deficient number, since it is larger than the sum of its proper divisors (23363).

1653661 is an equidigital number, since it uses as much as digits as its factorization.

1653661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23362.

The product of its digits is 3240, while the sum is 28.

The square root of 1653661 is about 1285.9475105929. The cubic root of 1653661 is about 118.2539060104.

The spelling of 1653661 in words is "one million, six hundred fifty-three thousand, six hundred sixty-one".