66961 has 4 divisors (see below), whose sum is σ = 69300. Its totient is φ = 64624.

The previous prime is 66959. The next prime is 66973. The reversal of 66961 is 16966.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 46225 + 20736 = 215^2 + 144^2 .

It is a cyclic number.

It is not a de Polignac number, because 66961 - 2¹ = 66959 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1126 + ... + 1183.

It is an arithmetic number, because the mean of its divisors is an integer number (17325).

2⁶⁶⁹⁶¹ is an apocalyptic number.

It is an amenable number.

66961 is a deficient number, since it is larger than the sum of its proper divisors (2339).

66961 is a wasteful number, since it uses less digits than its factorization.

66961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2338.

The product of its digits is 1944, while the sum is 28.

The square root of 66961 is about 258.7682360724. The cubic root of 66961 is about 40.6075988592.

The spelling of 66961 in words is "sixty-six thousand, nine hundred sixty-one".