661967 has 4 divisors (see below), whose sum is σ = 679896. Its totient is φ = 644040.

The previous prime is 661961. The next prime is 661987. The reversal of 661967 is 769166.

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 661967 - 2⁴ = 661951 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661961) 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, 8909 + ... + 8982.

It is an arithmetic number, because the mean of its divisors is an integer number (169974).

2⁶⁶¹⁹⁶⁷ is an apocalyptic number.

661967 is a deficient number, since it is larger than the sum of its proper divisors (17929).

661967 is a wasteful number, since it uses less digits than its factorization.

661967 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17928.

The product of its digits is 13608, while the sum is 35.

The square root of 661967 is about 813.6135446267. The cubic root of 661967 is about 87.1522853596.

The spelling of 661967 in words is "six hundred sixty-one thousand, nine hundred sixty-seven".