309481 has 2 divisors, whose sum is σ = 309482. Its totient is φ = 309480.

The previous prime is 309479. The next prime is 309493. The reversal of 309481 is 184903.

309481 is nontrivially palindromic in base 2.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 275625 + 33856 = 525^2 + 184^2 .

It is an emirp because it is prime and its reverse (184903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 309481 - 2¹ = 309479 is a prime.

It is a super-2 number, since 2×309481² = 191556978722, which contains 22 as substring.

Together with 309479, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (309461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154740 + 154741.

It is an arithmetic number, because the mean of its divisors is an integer number (154741).

2³⁰⁹⁴⁸¹ is an apocalyptic number.

It is an amenable number.

309481 is a deficient number, since it is larger than the sum of its proper divisors (1).

309481 is an equidigital number, since it uses as much as digits as its factorization.

309481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 309481 is about 556.3101652855. The cubic root of 309481 is about 67.6412041784.

The spelling of 309481 in words is "three hundred nine thousand, four hundred eighty-one".