308666021 has 2 divisors, whose sum is σ = 308666022. Its totient is φ = 308666020.

The previous prime is 308665979. The next prime is 308666023. The reversal of 308666021 is 120666803.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 216237025 + 92428996 = 14705^2 + 9614^2 .

It is an emirp because it is prime and its reverse (120666803) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 308666021 - 2¹⁰ = 308664997 is a prime.

Together with 308666023, 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 (308666023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154333010 + 154333011.

It is an arithmetic number, because the mean of its divisors is an integer number (154333011).

Almost surely, 2^308666021 is an apocalyptic number.

It is an amenable number.

308666021 is a deficient number, since it is larger than the sum of its proper divisors (1).

308666021 is an equidigital number, since it uses as much as digits as its factorization.

308666021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 308666021 is about 17568.8935622025. The cubic root of 308666021 is about 675.8177713649.

The spelling of 308666021 in words is "three hundred eight million, six hundred sixty-six thousand, twenty-one".