1378509546721 has 2 divisors, whose sum is σ = 1378509546722. Its totient is φ = 1378509546720.

The previous prime is 1378509546719. The next prime is 1378509546763. The reversal of 1378509546721 is 1276459058731.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1356572678400 + 21936868321 = 1164720^2 + 148111^2 .

It is a cyclic number.

It is not a de Polignac number, because 1378509546721 - 2¹ = 1378509546719 is a prime.

It is a super-4 number, since 4×1378509546721⁴ (a number of 50 digits) contains 4444 as substring.

Together with 1378509546719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1378509576721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 689254773360 + 689254773361.

It is an arithmetic number, because the mean of its divisors is an integer number (689254773361).

It is a 1-persistent number, because it is pandigital, but 2⋅1378509546721 = 2757019093442 is not.

Almost surely, 2^{1378509546721} is an apocalyptic number.

It is an amenable number.

1378509546721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1378509546721 is an equidigital number, since it uses as much as digits as its factorization.

1378509546721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12700800, while the sum is 58.

The spelling of 1378509546721 in words is "one trillion, three hundred seventy-eight billion, five hundred nine million, five hundred forty-six thousand, seven hundred twenty-one".