645731029 has 2 divisors, whose sum is σ = 645731030. Its totient is φ = 645731028.

The previous prime is 645731027. The next prime is 645731039. The reversal of 645731029 is 920137546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 377524900 + 268206129 = 19430^2 + 16377^2 .

It is a cyclic number.

It is not a de Polignac number, because 645731029 - 2¹ = 645731027 is a prime.

Together with 645731027, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645731027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322865514 + 322865515.

It is an arithmetic number, because the mean of its divisors is an integer number (322865515).

Almost surely, 2^645731029 is an apocalyptic number.

It is an amenable number.

645731029 is a deficient number, since it is larger than the sum of its proper divisors (1).

645731029 is an equidigital number, since it uses as much as digits as its factorization.

645731029 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45360, while the sum is 37.

The square root of 645731029 is about 25411.2382421636. The cubic root of 645731029 is about 864.3385541110.

The spelling of 645731029 in words is "six hundred forty-five million, seven hundred thirty-one thousand, twenty-nine".