1645408729 has 2 divisors, whose sum is σ = 1645408730. Its totient is φ = 1645408728.

The previous prime is 1645408727. The next prime is 1645408777. The reversal of 1645408729 is 9278045461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1536248025 + 109160704 = 39195^2 + 10448^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645408729 - 2¹ = 1645408727 is a prime.

Together with 1645408727, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1645408727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822704364 + 822704365.

It is an arithmetic number, because the mean of its divisors is an integer number (822704365).

Almost surely, 2^1645408729 is an apocalyptic number.

It is an amenable number.

1645408729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645408729 is an equidigital number, since it uses as much as digits as its factorization.

1645408729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 483840, while the sum is 46.

The square root of 1645408729 is about 40563.6380148527. The cubic root of 1645408729 is about 1180.5687024563.

The spelling of 1645408729 in words is "one billion, six hundred forty-five million, four hundred eight thousand, seven hundred twenty-nine".