645305431 has 4 divisors (see below), whose sum is σ = 683264592. Its totient is φ = 607346272.

The previous prime is 645305399. The next prime is 645305443. The reversal of 645305431 is 134503546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645305431 - 2⁵ = 645305399 is a prime.

It is a super-2 number, since 2×645305431² = 832838198556191522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645305393 and 645305402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645305491) 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, 18979555 + ... + 18979588.

It is an arithmetic number, because the mean of its divisors is an integer number (170816148).

Almost surely, 2^645305431 is an apocalyptic number.

645305431 is a deficient number, since it is larger than the sum of its proper divisors (37959161).

645305431 is a wasteful number, since it uses less digits than its factorization.

645305431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37959160.

The product of its (nonzero) digits is 21600, while the sum is 31.

The square root of 645305431 is about 25402.8626536459. The cubic root of 645305431 is about 864.1486186780.

Adding to 645305431 its reverse (134503546), we get a palindrome (779808977).

The spelling of 645305431 in words is "six hundred forty-five million, three hundred five thousand, four hundred thirty-one".