309430621 has 2 divisors, whose sum is σ = 309430622. Its totient is φ = 309430620.

The previous prime is 309430619. The next prime is 309430631. The reversal of 309430621 is 126034903.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 287472025 + 21958596 = 16955^2 + 4686^2 .

It is an emirp because it is prime and its reverse (126034903) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 309430621 - 2¹ = 309430619 is a prime.

Together with 309430619, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 309430621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (309430631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154715310 + 154715311.

It is an arithmetic number, because the mean of its divisors is an integer number (154715311).

Almost surely, 2^309430621 is an apocalyptic number.

It is an amenable number.

309430621 is a deficient number, since it is larger than the sum of its proper divisors (1).

309430621 is an equidigital number, since it uses as much as digits as its factorization.

309430621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 309430621 is about 17590.6401532178. The cubic root of 309430621 is about 676.3753364492.

The spelling of 309430621 in words is "three hundred nine million, four hundred thirty thousand, six hundred twenty-one".