645157 has 4 divisors (see below), whose sum is σ = 648076. Its totient is φ = 642240.

The previous prime is 645149. The next prime is 645179. The reversal of 645157 is 751546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 751546 = 2 ⋅375773.

It can be written as a sum of positive squares in 2 ways, for example, as 201601 + 443556 = 449^2 + 666^2 .

It is a cyclic number.

It is not a de Polignac number, because 645157 - 2³ = 645149 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 (645137) 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, 1098 + ... + 1579.

It is an arithmetic number, because the mean of its divisors is an integer number (162019).

2⁶⁴⁵¹⁵⁷ is an apocalyptic number.

It is an amenable number.

645157 is a deficient number, since it is larger than the sum of its proper divisors (2919).

645157 is a wasteful number, since it uses less digits than its factorization.

645157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2918.

The product of its digits is 4200, while the sum is 28.

The square root of 645157 is about 803.2166581938. The cubic root of 645157 is about 86.4082357404.

The spelling of 645157 in words is "six hundred forty-five thousand, one hundred fifty-seven".