1645894649 has 4 divisors (see below), whose sum is σ = 1881022464. Its totient is φ = 1410766836.

The previous prime is 1645894639. The next prime is 1645894669. The reversal of 1645894649 is 9464985461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1645894649 - 2⁴ = 1645894633 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1645894594 and 1645894603.

It is not an unprimeable number, because it can be changed into a prime (1645894639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117563897 + ... + 117563910.

It is an arithmetic number, because the mean of its divisors is an integer number (470255616).

Almost surely, 2^1645894649 is an apocalyptic number.

It is an amenable number.

1645894649 is a deficient number, since it is larger than the sum of its proper divisors (235127815).

1645894649 is an equidigital number, since it uses as much as digits as its factorization.

1645894649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235127814.

The product of its digits is 7464960, while the sum is 56.

The square root of 1645894649 is about 40569.6271735396. The cubic root of 1645894649 is about 1180.6849056975.

The spelling of 1645894649 in words is "one billion, six hundred forty-five million, eight hundred ninety-four thousand, six hundred forty-nine".