1645666739 has 2 divisors, whose sum is σ = 1645666740. Its totient is φ = 1645666738.

The previous prime is 1645666727. The next prime is 1645666747. The reversal of 1645666739 is 9376665461.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1645666739 - 2¹⁶ = 1645601203 is a prime.

It is not a weakly prime, because it can be changed into another prime (1645666769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822833369 + 822833370.

It is an arithmetic number, because the mean of its divisors is an integer number (822833370).

Almost surely, 2^1645666739 is an apocalyptic number.

1645666739 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645666739 is an equidigital number, since it uses as much as digits as its factorization.

1645666739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 53.

The square root of 1645666739 is about 40566.8182015795. The cubic root of 1645666739 is about 1180.6304059925.

The spelling of 1645666739 in words is "one billion, six hundred forty-five million, six hundred sixty-six thousand, seven hundred thirty-nine".