645241637 has 2 divisors, whose sum is σ = 645241638. Its totient is φ = 645241636.

The previous prime is 645241633. The next prime is 645241643. The reversal of 645241637 is 736142546.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644702881 + 538756 = 25391^2 + 734^2 .

It is a cyclic number.

It is not a de Polignac number, because 645241637 - 2² = 645241633 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645241637.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645241633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322620818 + 322620819.

It is an arithmetic number, because the mean of its divisors is an integer number (322620819).

Almost surely, 2^645241637 is an apocalyptic number.

It is an amenable number.

645241637 is a deficient number, since it is larger than the sum of its proper divisors (1).

645241637 is an equidigital number, since it uses as much as digits as its factorization.

645241637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 38.

The square root of 645241637 is about 25401.6069767249. The cubic root of 645241637 is about 864.1201415615.

Subtracting 645241637 from its reverse (736142546), we obtain a palindrome (90900909).

The spelling of 645241637 in words is "six hundred forty-five million, two hundred forty-one thousand, six hundred thirty-seven".