645131 has 2 divisors, whose sum is σ = 645132. Its totient is φ = 645130.

The previous prime is 645097. The next prime is 645137. The reversal of 645131 is 131546.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645131 - 2⁶ = 645067 is a prime.

It is a super-2 number, since 2×645131² = 832388014322, which contains 22 as substring.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645131.

It is not a weakly prime, because it can be changed into another prime (645137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322565 + 322566.

It is an arithmetic number, because the mean of its divisors is an integer number (322566).

2⁶⁴⁵¹³¹ is an apocalyptic number.

645131 is a deficient number, since it is larger than the sum of its proper divisors (1).

645131 is an equidigital number, since it uses as much as digits as its factorization.

645131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 360, while the sum is 20.

The square root of 645131 is about 803.2004731074. The cubic root of 645131 is about 86.4070749665.

Adding to 645131 its reverse (131546), we get a palindrome (776677).

The spelling of 645131 in words is "six hundred forty-five thousand, one hundred thirty-one".