645786261 has 12 divisors (see below), whose sum is σ = 933310560. Its totient is φ = 430289640.

The previous prime is 645786247. The next prime is 645786263. The reversal of 645786261 is 162687546.

It is not a de Polignac number, because 645786261 - 2²² = 641591957 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645786263) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1201 + ... + 35958.

It is an arithmetic number, because the mean of its divisors is an integer number (77775880).

Almost surely, 2^645786261 is an apocalyptic number.

It is an amenable number.

645786261 is a deficient number, since it is larger than the sum of its proper divisors (287524299).

645786261 is a wasteful number, since it uses less digits than its factorization.

645786261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39096 (or 39093 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

The square root of 645786261 is about 25412.3249821814. The cubic root of 645786261 is about 864.3631968719.

The spelling of 645786261 in words is "six hundred forty-five million, seven hundred eighty-six thousand, two hundred sixty-one".