645593261 has 2 divisors, whose sum is σ = 645593262. Its totient is φ = 645593260.

The previous prime is 645593243. The next prime is 645593287. The reversal of 645593261 is 162395546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 569729161 + 75864100 = 23869^2 + 8710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645593261 is a prime.

It is a super-2 number, since 2×645593261² = 833581317297228242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645592261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322796630 + 322796631.

It is an arithmetic number, because the mean of its divisors is an integer number (322796631).

Almost surely, 2^645593261 is an apocalyptic number.

It is an amenable number.

645593261 is a deficient number, since it is larger than the sum of its proper divisors (1).

645593261 is an equidigital number, since it uses as much as digits as its factorization.

645593261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 194400, while the sum is 41.

The square root of 645593261 is about 25408.5273284384. The cubic root of 645593261 is about 864.2770802888.

The spelling of 645593261 in words is "six hundred forty-five million, five hundred ninety-three thousand, two hundred sixty-one".