278740981 has 2 divisors, whose sum is σ = 278740982. Its totient is φ = 278740980.

The previous prime is 278740967. The next prime is 278740991. The reversal of 278740981 is 189047872.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 278723025 + 17956 = 16695^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 278740981 - 2⁵ = 278740949 is a prime.

It is a super-2 number, since 2×278740981² = 155393068977684722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278740951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139370490 + 139370491.

It is an arithmetic number, because the mean of its divisors is an integer number (139370491).

Almost surely, 2^278740981 is an apocalyptic number.

It is an amenable number.

278740981 is a deficient number, since it is larger than the sum of its proper divisors (1).

278740981 is an equidigital number, since it uses as much as digits as its factorization.

278740981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 225792, while the sum is 46.

The square root of 278740981 is about 16695.5377571374. The cubic root of 278740981 is about 653.2312328012.

The spelling of 278740981 in words is "two hundred seventy-eight million, seven hundred forty thousand, nine hundred eighty-one".