278122321 has 2 divisors, whose sum is σ = 278122322. Its totient is φ = 278122320.

The previous prime is 278122319. The next prime is 278122331. The reversal of 278122321 is 123221872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 250873921 + 27248400 = 15839^2 + 5220^2 .

It is a cyclic number.

It is not a de Polignac number, because 278122321 - 2¹ = 278122319 is a prime.

Together with 278122319, 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 278122321.

It is not a weakly prime, because it can be changed into another prime (278122331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139061160 + 139061161.

It is an arithmetic number, because the mean of its divisors is an integer number (139061161).

Almost surely, 2^278122321 is an apocalyptic number.

It is an amenable number.

278122321 is a deficient number, since it is larger than the sum of its proper divisors (1).

278122321 is an equidigital number, since it uses as much as digits as its factorization.

278122321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 28.

The square root of 278122321 is about 16676.9997601487. Note that the first 3 decimals coincide. The cubic root of 278122321 is about 652.7475969578.

The spelling of 278122321 in words is "two hundred seventy-eight million, one hundred twenty-two thousand, three hundred twenty-one".