645739013 has 4 divisors (see below), whose sum is σ = 646366368. Its totient is φ = 645111660.

The previous prime is 645738937. The next prime is 645739049. The reversal of 645739013 is 310937546.

It is a happy number.

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 645739013 - 2⁸ = 645738757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645039013) 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, 312131 + ... + 314192.

It is an arithmetic number, because the mean of its divisors is an integer number (161591592).

Almost surely, 2^645739013 is an apocalyptic number.

It is an amenable number.

645739013 is a deficient number, since it is larger than the sum of its proper divisors (627355).

645739013 is a wasteful number, since it uses less digits than its factorization.

645739013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627354.

The product of its (nonzero) digits is 68040, while the sum is 38.

The square root of 645739013 is about 25411.3953375252. The cubic root of 645739013 is about 864.3421164047.

The spelling of 645739013 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, thirteen".