1661213 has 8 divisors (see below), whose sum is σ = 1710456. Its totient is φ = 1612800.

The previous prime is 1661173. The next prime is 1661237. The reversal of 1661213 is 3121661.

It can be written as a sum of positive squares in 4 ways, for example, as 17689 + 1643524 = 133^2 + 1282^2 .

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 1661213 - 2⁸ = 1660957 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 (1661243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6773 + ... + 7013.

It is an arithmetic number, because the mean of its divisors is an integer number (213807).

2^1661213 is an apocalyptic number.

It is an amenable number.

1661213 is a deficient number, since it is larger than the sum of its proper divisors (49243).

1661213 is a wasteful number, since it uses less digits than its factorization.

1661213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415.

The product of its digits is 216, while the sum is 20.

The square root of 1661213 is about 1288.8805220035. The cubic root of 1661213 is about 118.4336481019.

Adding to 1661213 its reverse (3121661), we get a palindrome (4782874).

The spelling of 1661213 in words is "one million, six hundred sixty-one thousand, two hundred thirteen".