645840529 has 4 divisors (see below), whose sum is σ = 673920576. Its totient is φ = 617760484.

The previous prime is 645840511. The next prime is 645840541. The reversal of 645840529 is 925048546.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 645840529 - 2¹⁹ = 645316241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645840509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14039989 + ... + 14040034.

It is an arithmetic number, because the mean of its divisors is an integer number (168480144).

Almost surely, 2^645840529 is an apocalyptic number.

It is an amenable number.

645840529 is a deficient number, since it is larger than the sum of its proper divisors (28080047).

645840529 is a wasteful number, since it uses less digits than its factorization.

645840529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28080046.

The product of its (nonzero) digits is 345600, while the sum is 43.

The square root of 645840529 is about 25413.3927093570. The cubic root of 645840529 is about 864.3874081582.

The spelling of 645840529 in words is "six hundred forty-five million, eight hundred forty thousand, five hundred twenty-nine".