645724440437 has 2 divisors, whose sum is σ = 645724440438. Its totient is φ = 645724440436.

The previous prime is 645724440409. The next prime is 645724440461. The reversal of 645724440437 is 734044427546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 473407298116 + 172317142321 = 688046^2 + 415111^2 .

It is a cyclic number.

It is not a de Polignac number, because 645724440437 - 2¹⁰ = 645724439413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645724440037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322862220218 + 322862220219.

It is an arithmetic number, because the mean of its divisors is an integer number (322862220219).

Almost surely, 2^645724440437 is an apocalyptic number.

It is an amenable number.

645724440437 is a deficient number, since it is larger than the sum of its proper divisors (1).

645724440437 is an equidigital number, since it uses as much as digits as its factorization.

645724440437 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9031680, while the sum is 50.

The spelling of 645724440437 in words is "six hundred forty-five billion, seven hundred twenty-four million, four hundred forty thousand, four hundred thirty-seven".