309868421 has 2 divisors, whose sum is σ = 309868422. Its totient is φ = 309868420.

The previous prime is 309868411. The next prime is 309868423. The reversal of 309868421 is 124868903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 276390625 + 33477796 = 16625^2 + 5786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-309868421 is a prime.

Together with 309868423, 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 (309868423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154934210 + 154934211.

It is an arithmetic number, because the mean of its divisors is an integer number (154934211).

Almost surely, 2^309868421 is an apocalyptic number.

It is an amenable number.

309868421 is a deficient number, since it is larger than the sum of its proper divisors (1).

309868421 is an equidigital number, since it uses as much as digits as its factorization.

309868421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 82944, while the sum is 41.

The square root of 309868421 is about 17603.0798725678. The cubic root of 309868421 is about 676.6941775264.

The spelling of 309868421 in words is "three hundred nine million, eight hundred sixty-eight thousand, four hundred twenty-one".