645290993 has 4 divisors (see below), whose sum is σ = 645356400. Its totient is φ = 645225588.

The previous prime is 645290969. The next prime is 645291043. The reversal of 645290993 is 399092546.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645290993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645290963) 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, 14543 + ... + 38756.

It is an arithmetic number, because the mean of its divisors is an integer number (161339100).

Almost surely, 2^645290993 is an apocalyptic number.

It is an amenable number.

645290993 is a deficient number, since it is larger than the sum of its proper divisors (65407).

645290993 is a wasteful number, since it uses less digits than its factorization.

645290993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65406.

The product of its (nonzero) digits is 524880, while the sum is 47.

The square root of 645290993 is about 25402.5784714859. The cubic root of 645290993 is about 864.1421738379.

The spelling of 645290993 in words is "six hundred forty-five million, two hundred ninety thousand, nine hundred ninety-three".