278798651981 has 2 divisors, whose sum is σ = 278798651982. Its totient is φ = 278798651980.

The previous prime is 278798651977. The next prime is 278798652017. The reversal of 278798651981 is 189156897872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 278520062500 + 278589481 = 527750^2 + 16691^2 .

It is a cyclic number.

It is not a de Polignac number, because 278798651981 - 2² = 278798651977 is a prime.

It is a super-2 number, since 2×278798651981² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278798651941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139399325990 + 139399325991.

It is an arithmetic number, because the mean of its divisors is an integer number (139399325991).

Almost surely, 2^278798651981 is an apocalyptic number.

It is an amenable number.

278798651981 is a deficient number, since it is larger than the sum of its proper divisors (1).

278798651981 is an equidigital number, since it uses as much as digits as its factorization.

278798651981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 121927680, while the sum is 71.

The spelling of 278798651981 in words is "two hundred seventy-eight billion, seven hundred ninety-eight million, six hundred fifty-one thousand, nine hundred eighty-one".