661213 has 8 divisors (see below), whose sum is σ = 768960. Its totient is φ = 556800.

The previous prime is 661201. The next prime is 661217. The reversal of 661213 is 312166.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661213 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 (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 7 ways as a sum of consecutive naturals, for example, 388 + ... + 1213.

It is an arithmetic number, because the mean of its divisors is an integer number (96120).

2⁶⁶¹²¹³ is an apocalyptic number.

It is an amenable number.

661213 is a deficient number, since it is larger than the sum of its proper divisors (107747).

661213 is a wasteful number, since it uses less digits than its factorization.

661213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1667.

The product of its digits is 216, while the sum is 19.

The square root of 661213 is about 813.1500476542. The cubic root of 661213 is about 87.1191831111.

Adding to 661213 its reverse (312166), we get a palindrome (973379).

The spelling of 661213 in words is "six hundred sixty-one thousand, two hundred thirteen".