645206871 has 4 divisors (see below), whose sum is σ = 860275832. Its totient is φ = 430137912.

The previous prime is 645206869. The next prime is 645206893. The reversal of 645206871 is 178602546.

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

It is not a de Polignac number, because 645206871 - 2¹ = 645206869 is a prime.

It is a super-2 number, since 2×645206871² = 832583812771221282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645206801) 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, 107534476 + ... + 107534481.

It is an arithmetic number, because the mean of its divisors is an integer number (215068958).

Almost surely, 2^645206871 is an apocalyptic number.

645206871 is a deficient number, since it is larger than the sum of its proper divisors (215068961).

645206871 is a wasteful number, since it uses less digits than its factorization.

645206871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215068960.

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 645206871 is about 25400.9226407231. The cubic root of 645206871 is about 864.1046215151.

The spelling of 645206871 in words is "six hundred forty-five million, two hundred six thousand, eight hundred seventy-one".