645617243 has 6 divisors (see below), whose sum is σ = 653630124. Its totient is φ = 637610024.

The previous prime is 645617237. The next prime is 645617257. The reversal of 645617243 is 342716546.

It is a happy number.

It is not a de Polignac number, because 645617243 - 2¹² = 645613147 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645617197 and 645617206.

It is not an unprimeable number, because it can be changed into a prime (645617263) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 230093 + ... + 232881.

It is an arithmetic number, because the mean of its divisors is an integer number (108938354).

Almost surely, 2^645617243 is an apocalyptic number.

645617243 is a deficient number, since it is larger than the sum of its proper divisors (8012881).

645617243 is an frugal number, since it uses more digits than its factorization.

645617243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5661 (or 2872 counting only the distinct ones).

The product of its digits is 120960, while the sum is 38.

The square root of 645617243 is about 25408.9992522334. Note that the first 3 decimals coincide. The cubic root of 645617243 is about 864.2877819889.

Adding to 645617243 its sum of digits (38), we get a square (645617281 = 25409²).

The spelling of 645617243 in words is "six hundred forty-five million, six hundred seventeen thousand, two hundred forty-three".