1645894639 has 2 divisors, whose sum is σ = 1645894640. Its totient is φ = 1645894638.

The previous prime is 1645894633. The next prime is 1645894669. The reversal of 1645894639 is 9364985461.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1645894639 - 2⁷ = 1645894511 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1645894639.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1645894633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822947319 + 822947320.

It is an arithmetic number, because the mean of its divisors is an integer number (822947320).

Almost surely, 2^1645894639 is an apocalyptic number.

1645894639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645894639 is an equidigital number, since it uses as much as digits as its factorization.

1645894639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5598720, while the sum is 55.

The square root of 1645894639 is about 40569.6270502947. The cubic root of 1645894639 is about 1180.6849033063.

The spelling of 1645894639 in words is "one billion, six hundred forty-five million, eight hundred ninety-four thousand, six hundred thirty-nine".