645101 has 4 divisors (see below), whose sum is σ = 654012. Its totient is φ = 636192.

The previous prime is 645097. The next prime is 645131. The reversal of 645101 is 101546.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 101546 = 2 ⋅50773.

It can be written as a sum of positive squares in 2 ways, for example, as 561001 + 84100 = 749^2 + 290^2 .

It is a cyclic number.

It is not a de Polignac number, because 645101 - 2² = 645097 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 645101.

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 645101.

It is not an unprimeable number, because it can be changed into a prime (645131) 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, 4346 + ... + 4491.

It is an arithmetic number, because the mean of its divisors is an integer number (163503).

2⁶⁴⁵¹⁰¹ is an apocalyptic number.

It is an amenable number.

645101 is a deficient number, since it is larger than the sum of its proper divisors (8911).

645101 is an equidigital number, since it uses as much as digits as its factorization.

645101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8910.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 645101 is about 803.1817976025. The cubic root of 645101 is about 86.4057355732.

Adding to 645101 its reverse (101546), we get a palindrome (746647).

The spelling of 645101 in words is "six hundred forty-five thousand, one hundred one".