645444157 has 2 divisors, whose sum is σ = 645444158. Its totient is φ = 645444156.

The previous prime is 645444139. The next prime is 645444161. The reversal of 645444157 is 751444546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 380601081 + 264843076 = 19509^2 + 16274^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645444157 is a prime.

It is a Chen prime.

It is equal to p_33568690 and since 645444157 and 33568690 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645444167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322722078 + 322722079.

It is an arithmetic number, because the mean of its divisors is an integer number (322722079).

Almost surely, 2^645444157 is an apocalyptic number.

It is an amenable number.

645444157 is a deficient number, since it is larger than the sum of its proper divisors (1).

645444157 is an equidigital number, since it uses as much as digits as its factorization.

645444157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 268800, while the sum is 40.

The square root of 645444157 is about 25405.5930259461. The cubic root of 645444157 is about 864.2105383448.

The spelling of 645444157 in words is "six hundred forty-five million, four hundred forty-four thousand, one hundred fifty-seven".