308399981 has 2 divisors, whose sum is σ = 308399982. Its totient is φ = 308399980.

The previous prime is 308399969. The next prime is 308399983. The reversal of 308399981 is 189993803.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 305935081 + 2464900 = 17491^2 + 1570^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-308399981 is a prime.

It is a super-2 number, since 2×308399981² = 190221096561600722, which contains 22 as substring.

Together with 308399983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (308399983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154199990 + 154199991.

It is an arithmetic number, because the mean of its divisors is an integer number (154199991).

Almost surely, 2^308399981 is an apocalyptic number.

It is an amenable number.

308399981 is a deficient number, since it is larger than the sum of its proper divisors (1).

308399981 is an equidigital number, since it uses as much as digits as its factorization.

308399981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 419904, while the sum is 50.

The square root of 308399981 is about 17561.3205938506. The cubic root of 308399981 is about 675.6235525571.

The spelling of 308399981 in words is "three hundred eight million, three hundred ninety-nine thousand, nine hundred eighty-one".