645071 has 4 divisors (see below), whose sum is σ = 737232. Its totient is φ = 552912.

The previous prime is 645067. The next prime is 645077. The reversal of 645071 is 170546.

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 645071 - 2² = 645067 is a prime.

It is a super-2 number, since 2×645071² = 832233190082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645071.

It is not an unprimeable number, because it can be changed into a prime (645077) 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, 46070 + ... + 46083.

It is an arithmetic number, because the mean of its divisors is an integer number (184308).

2⁶⁴⁵⁰⁷¹ is an apocalyptic number.

645071 is a deficient number, since it is larger than the sum of its proper divisors (92161).

645071 is an equidigital number, since it uses as much as digits as its factorization.

645071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92160.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 645071 is about 803.1631216633. The cubic root of 645071 is about 86.4043961383.

The spelling of 645071 in words is "six hundred forty-five thousand, seventy-one".