1645263517 has 4 divisors (see below), whose sum is σ = 1646616636. Its totient is φ = 1643910400.

The previous prime is 1645263511. The next prime is 1645263541. The reversal of 1645263517 is 7153625461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7153625461 = 1031 ⋅6938531.

It can be written as a sum of positive squares in 2 ways, for example, as 401361156 + 1243902361 = 20034^2 + 35269^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645263517 - 2³ = 1645263509 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 1645263517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645263511) 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, 674734 + ... + 677167.

It is an arithmetic number, because the mean of its divisors is an integer number (411654159).

Almost surely, 2^1645263517 is an apocalyptic number.

It is an amenable number.

1645263517 is a deficient number, since it is larger than the sum of its proper divisors (1353119).

1645263517 is a wasteful number, since it uses less digits than its factorization.

1645263517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1353118.

The product of its digits is 151200, while the sum is 40.

The square root of 1645263517 is about 40561.8480471489. The cubic root of 1645263517 is about 1180.5339719194.

Adding to 1645263517 its reverse (7153625461), we get a palindrome (8798888978).

The spelling of 1645263517 in words is "one billion, six hundred forty-five million, two hundred sixty-three thousand, five hundred seventeen".