278851981 has 2 divisors, whose sum is σ = 278851982. Its totient is φ = 278851980.

The previous prime is 278851973. The next prime is 278852009. The reversal of 278851981 is 189158872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162945225 + 115906756 = 12765^2 + 10766^2 .

It is a cyclic number.

It is not a de Polignac number, because 278851981 - 2³ = 278851973 is a prime.

It is a super-2 number, since 2×278851981² = 155516854615248722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278851381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139425990 + 139425991.

It is an arithmetic number, because the mean of its divisors is an integer number (139425991).

Almost surely, 2^278851981 is an apocalyptic number.

It is an amenable number.

278851981 is a deficient number, since it is larger than the sum of its proper divisors (1).

278851981 is an equidigital number, since it uses as much as digits as its factorization.

278851981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 322560, while the sum is 49.

The square root of 278851981 is about 16698.8616677904. The cubic root of 278851981 is about 653.3179310254.

The spelling of 278851981 in words is "two hundred seventy-eight million, eight hundred fifty-one thousand, nine hundred eighty-one".