645516271 has 4 divisors (see below), whose sum is σ = 645841512. Its totient is φ = 645191032.

The previous prime is 645516253. The next prime is 645516281. The reversal of 645516271 is 172615546.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 645516271 - 2⁵ = 645516239 is a prime.

It is a super-2 number, since 2×645516271² = 833382512251490882, which contains 22 as substring.

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 645516271.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645516251) 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, 159625 + ... + 163618.

It is an arithmetic number, because the mean of its divisors is an integer number (161460378).

Almost surely, 2^645516271 is an apocalyptic number.

645516271 is a deficient number, since it is larger than the sum of its proper divisors (325241).

645516271 is a wasteful number, since it uses less digits than its factorization.

645516271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325240.

The product of its digits is 50400, while the sum is 37.

The square root of 645516271 is about 25407.0122407181. The cubic root of 645516271 is about 864.2427225687.

The spelling of 645516271 in words is "six hundred forty-five million, five hundred sixteen thousand, two hundred seventy-one".