1278958721 has 2 divisors, whose sum is σ = 1278958722. Its totient is φ = 1278958720.

The previous prime is 1278958717. The next prime is 1278958727. The reversal of 1278958721 is 1278598721.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 657204496 + 621754225 = 25636^2 + 24935^2 .

It is a cyclic number.

It is not a de Polignac number, because 1278958721 - 2² = 1278958717 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1278958721.

It is not a weakly prime, because it can be changed into another prime (1278958727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639479360 + 639479361.

It is an arithmetic number, because the mean of its divisors is an integer number (639479361).

Almost surely, 2^1278958721 is an apocalyptic number.

It is an amenable number.

1278958721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278958721 is an equidigital number, since it uses as much as digits as its factorization.

1278958721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 564480, while the sum is 50.

The square root of 1278958721 is about 35762.5323627956. The cubic root of 1278958721 is about 1085.4725432160.

Subtracting from 1278958721 its reverse (1278598721), we obtain a square (360000 = 600²).

The spelling of 1278958721 in words is "one billion, two hundred seventy-eight million, nine hundred fifty-eight thousand, seven hundred twenty-one".