1645787899 has 4 divisors (see below), whose sum is σ = 1880900464. Its totient is φ = 1410675336.

The previous prime is 1645787893. The next prime is 1645787951. The reversal of 1645787899 is 9987875461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9987875461 = 31 ⋅322189531.

It is not a de Polignac number, because 1645787899 - 2⁹ = 1645787387 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1645787899.

It is not an unprimeable number, because it can be changed into a prime (1645787893) 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, 117556272 + ... + 117556285.

It is an arithmetic number, because the mean of its divisors is an integer number (470225116).

Almost surely, 2^1645787899 is an apocalyptic number.

1645787899 is a deficient number, since it is larger than the sum of its proper divisors (235112565).

1645787899 is an equidigital number, since it uses as much as digits as its factorization.

1645787899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235112564.

The product of its digits is 30481920, while the sum is 64.

The square root of 1645787899 is about 40568.3115128052. The cubic root of 1645787899 is about 1180.6593793900.

The spelling of 1645787899 in words is "one billion, six hundred forty-five million, seven hundred eighty-seven thousand, eight hundred ninety-nine".