1661425 has 6 divisors (see below), whose sum is σ = 2060198. Its totient is φ = 1329120.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661425 is 5241661.

It can be written as a sum of positive squares in 3 ways, for example, as 12769 + 1648656 = 113^2 + 1284^2 .

It is not a de Polignac number, because 1661425 - 2¹⁹ = 1137137 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 66457 = 1661425 / (1 + 6 + 6 + 1 + 4 + 2 + 5).

It is a Duffinian number.

1661425 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661425.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 33204 + ... + 33253.

2^1661425 is an apocalyptic number.

It is an amenable number.

1661425 is a deficient number, since it is larger than the sum of its proper divisors (398773).

1661425 is an equidigital number, since it uses as much as digits as its factorization.

1661425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66467 (or 66462 counting only the distinct ones).

The product of its digits is 1440, while the sum is 25.

The square root of 1661425 is about 1288.9627612930. The cubic root of 1661425 is about 118.4386859599.

The spelling of 1661425 in words is "one million, six hundred sixty-one thousand, four hundred twenty-five".