19278046721 has 2 divisors, whose sum is σ = 19278046722. Its totient is φ = 19278046720.

The previous prime is 19278046691. The next prime is 19278046769. The reversal of 19278046721 is 12764087291.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12959545600 + 6318501121 = 113840^2 + 79489^2 .

It is a cyclic number.

It is not a de Polignac number, because 19278046721 - 2¹⁴ = 19278030337 is a prime.

It is not a weakly prime, because it can be changed into another prime (19278046421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9639023360 + 9639023361.

It is an arithmetic number, because the mean of its divisors is an integer number (9639023361).

Almost surely, 2^19278046721 is an apocalyptic number.

It is an amenable number.

19278046721 is a deficient number, since it is larger than the sum of its proper divisors (1).

19278046721 is an equidigital number, since it uses as much as digits as its factorization.

19278046721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 338688, while the sum is 47.

The spelling of 19278046721 in words is "nineteen billion, two hundred seventy-eight million, forty-six thousand, seven hundred twenty-one".