309961 has 4 divisors (see below), whose sum is σ = 328212. Its totient is φ = 291712.

The previous prime is 309937. The next prime is 309977. The reversal of 309961 is 169903.

It is a happy number.

309961 is nontrivially palindromic in base 8.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 169903 = 71 ⋅2393.

It can be written as a sum of positive squares in 2 ways, for example, as 219961 + 90000 = 469^2 + 300^2 .

It is a cyclic number.

It is not a de Polignac number, because 309961 - 2⁵ = 309929 is a prime.

It is a Duffinian number.

309961 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (309931) 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, 9100 + ... + 9133.

It is an arithmetic number, because the mean of its divisors is an integer number (82053).

2³⁰⁹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

309961 is a deficient number, since it is larger than the sum of its proper divisors (18251).

309961 is a wasteful number, since it uses less digits than its factorization.

309961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18250.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 309961 is about 556.7414121475. The cubic root of 309961 is about 67.6761562507.

It can be divided in two parts, 3099 and 61, that added together give a triangular number (3160 = T₇₉).

The spelling of 309961 in words is "three hundred nine thousand, nine hundred sixty-one".