1661897 has 8 divisors (see below), whose sum is σ = 1710720. Its totient is φ = 1613920.

The previous prime is 1661893. The next prime is 1661899. The reversal of 1661897 is 7981661.

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

It is a cyclic number.

It is not a de Polignac number, because 1661897 - 2² = 1661893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661897.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661893) 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, 6188 + ... + 6450.

It is an arithmetic number, because the mean of its divisors is an integer number (213840).

2^1661897 is an apocalyptic number.

It is an amenable number.

1661897 is a deficient number, since it is larger than the sum of its proper divisors (48823).

1661897 is an equidigital number, since it uses as much as digits as its factorization.

1661897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423.

The product of its digits is 18144, while the sum is 38.

The square root of 1661897 is about 1289.1458412453. The cubic root of 1661897 is about 118.4499007838.

The spelling of 1661897 in words is "one million, six hundred sixty-one thousand, eight hundred ninety-seven".