661211 has 4 divisors (see below), whose sum is σ = 676632. Its totient is φ = 645792.

The previous prime is 661201. The next prime is 661217. The reversal of 661211 is 112166.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661211 - 2¹⁸ = 399067 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 661211.

It is not an unprimeable number, because it can be changed into a prime (661217) 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 3 ways as a sum of consecutive naturals, for example, 7646 + ... + 7731.

It is an arithmetic number, because the mean of its divisors is an integer number (169158).

2⁶⁶¹²¹¹ is an apocalyptic number.

661211 is a deficient number, since it is larger than the sum of its proper divisors (15421).

661211 is a wasteful number, since it uses less digits than its factorization.

661211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15420.

The product of its digits is 72, while the sum is 17.

The square root of 661211 is about 813.1488178679. The cubic root of 661211 is about 87.1190952732.

Adding to 661211 its reverse (112166), we get a palindrome (773377).

The spelling of 661211 in words is "six hundred sixty-one thousand, two hundred eleven".