1245728309261 has 2 divisors, whose sum is σ = 1245728309262. Its totient is φ = 1245728309260.

The previous prime is 1245728309209. The next prime is 1245728309299. The reversal of 1245728309261 is 1629038275421.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 823220509225 + 422507800036 = 907315^2 + 650006^2 .

It is a cyclic number.

It is not a de Polignac number, because 1245728309261 - 2¹⁸ = 1245728047117 is a prime.

It is a super-2 number, since 2×1245728309261² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1245728309561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 622864154630 + 622864154631.

It is an arithmetic number, because the mean of its divisors is an integer number (622864154631).

It is a 1-persistent number, because it is pandigital, but 2⋅1245728309261 = 2491456618522 is not.

Almost surely, 2^{1245728309261} is an apocalyptic number.

It is an amenable number.

1245728309261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1245728309261 is an equidigital number, since it uses as much as digits as its factorization.

1245728309261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1451520, while the sum is 50.

The spelling of 1245728309261 in words is "one trillion, two hundred forty-five billion, seven hundred twenty-eight million, three hundred nine thousand, two hundred sixty-one".