128316421 has 2 divisors, whose sum is σ = 128316422. Its totient is φ = 128316420.

The previous prime is 128316403. The next prime is 128316427. The reversal of 128316421 is 124613821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74132100 + 54184321 = 8610^2 + 7361^2 .

It is an emirp because it is prime and its reverse (124613821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128316421 - 2⁵ = 128316389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128316421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128316427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64158210 + 64158211.

It is an arithmetic number, because the mean of its divisors is an integer number (64158211).

Almost surely, 2^128316421 is an apocalyptic number.

It is an amenable number.

128316421 is a deficient number, since it is larger than the sum of its proper divisors (1).

128316421 is an equidigital number, since it uses as much as digits as its factorization.

128316421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 28.

The square root of 128316421 is about 11327.6838320991. The cubic root of 128316421 is about 504.3833547740.

The spelling of 128316421 in words is "one hundred twenty-eight million, three hundred sixteen thousand, four hundred twenty-one".