645515639 has 2 divisors, whose sum is σ = 645515640. Its totient is φ = 645515638.

The previous prime is 645515627. The next prime is 645515657. The reversal of 645515639 is 936515546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645515639 - 2⁸ = 645515383 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645515639.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645515609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322757819 + 322757820.

It is an arithmetic number, because the mean of its divisors is an integer number (322757820).

Almost surely, 2^645515639 is an apocalyptic number.

645515639 is a deficient number, since it is larger than the sum of its proper divisors (1).

645515639 is an equidigital number, since it uses as much as digits as its factorization.

645515639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 486000, while the sum is 44.

The square root of 645515639 is about 25406.9998032038. Note that the first 3 decimals coincide. The cubic root of 645515639 is about 864.2424405198.

The spelling of 645515639 in words is "six hundred forty-five million, five hundred fifteen thousand, six hundred thirty-nine".