278426989 has 2 divisors, whose sum is σ = 278426990. Its totient is φ = 278426988.

The previous prime is 278426987. The next prime is 278427031. The reversal of 278426989 is 989624872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187224489 + 91202500 = 13683^2 + 9550^2 .

It is a cyclic number.

It is not a de Polignac number, because 278426989 - 2¹ = 278426987 is a prime.

It is a super-2 number, since 2×278426989² = 155043176407212242, which contains 22 as substring.

Together with 278426987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278426987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139213494 + 139213495.

It is an arithmetic number, because the mean of its divisors is an integer number (139213495).

Almost surely, 2^278426989 is an apocalyptic number.

It is an amenable number.

278426989 is a deficient number, since it is larger than the sum of its proper divisors (1).

278426989 is an equidigital number, since it uses as much as digits as its factorization.

278426989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3483648, while the sum is 55.

The square root of 278426989 is about 16686.1316367815. The cubic root of 278426989 is about 652.9858599047.

The spelling of 278426989 in words is "two hundred seventy-eight million, four hundred twenty-six thousand, nine hundred eighty-nine".