645907203871 has 4 divisors (see below), whose sum is σ = 645909033744. Its totient is φ = 645905374000.

The previous prime is 645907203863. The next prime is 645907203889. The reversal of 645907203871 is 178302709546.

645907203871 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 645907203871 - 2³ = 645907203863 is a prime.

It is a super-2 number, since 2×645907203871² (a number of 24 digits) 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 (645907201871) 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, 198430 + ... + 1153771.

It is an arithmetic number, because the mean of its divisors is an integer number (161477258436).

It is a 1-persistent number, because it is pandigital, but 2⋅645907203871 = 1291814407742 is not.

Almost surely, 2^645907203871 is an apocalyptic number.

645907203871 is a deficient number, since it is larger than the sum of its proper divisors (1829873).

645907203871 is a wasteful number, since it uses less digits than its factorization.

645907203871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1829872.

The product of its (nonzero) digits is 2540160, while the sum is 52.

The spelling of 645907203871 in words is "six hundred forty-five billion, nine hundred seven million, two hundred three thousand, eight hundred seventy-one".