645431361 has 4 divisors (see below), whose sum is σ = 860575152. Its totient is φ = 430287572.

The previous prime is 645431357. The next prime is 645431417. The reversal of 645431361 is 163134546.

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 645431361 - 2² = 645431357 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645431351) 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, 107571891 + ... + 107571896.

It is an arithmetic number, because the mean of its divisors is an integer number (215143788).

Almost surely, 2^645431361 is an apocalyptic number.

It is an amenable number.

645431361 is a deficient number, since it is larger than the sum of its proper divisors (215143791).

645431361 is a wasteful number, since it uses less digits than its factorization.

645431361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215143790.

The product of its digits is 25920, while the sum is 33.

The square root of 645431361 is about 25405.3411903875. The cubic root of 645431361 is about 864.2048272847.

The spelling of 645431361 in words is "six hundred forty-five million, four hundred thirty-one thousand, three hundred sixty-one".