1645312687 has 4 divisors (see below), whose sum is σ = 1650027400. Its totient is φ = 1640597976.

The previous prime is 1645312681. The next prime is 1645312703. The reversal of 1645312687 is 7862135461.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1645312687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645312681) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2356833 + ... + 2357530.

It is an arithmetic number, because the mean of its divisors is an integer number (412506850).

Almost surely, 2^1645312687 is an apocalyptic number.

1645312687 is a deficient number, since it is larger than the sum of its proper divisors (4714713).

1645312687 is an equidigital number, since it uses as much as digits as its factorization.

1645312687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4714712.

The product of its digits is 241920, while the sum is 43.

The square root of 1645312687 is about 40562.4541540573. The cubic root of 1645312687 is about 1180.5457321990.

The spelling of 1645312687 in words is "one billion, six hundred forty-five million, three hundred twelve thousand, six hundred eighty-seven".