645771127 has 4 divisors (see below), whose sum is σ = 645823000. Its totient is φ = 645719256.

The previous prime is 645771097. The next prime is 645771151. The reversal of 645771127 is 721177546.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 721177546 = 2 ⋅360588773.

It is a 3-Lehmer number, since φ(645771127) divides (645771127-1)³.

It is a cyclic number.

It is not a de Polignac number, because 645771127 - 2⁷ = 645770999 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645771127.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645771227) 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, 5188 + ... + 36310.

It is an arithmetic number, because the mean of its divisors is an integer number (161455750).

Almost surely, 2^645771127 is an apocalyptic number.

645771127 is the 20749-th pentagonal number.

645771127 is a deficient number, since it is larger than the sum of its proper divisors (51873).

645771127 is a wasteful number, since it uses less digits than its factorization.

645771127 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51872.

The product of its digits is 82320, while the sum is 40.

The square root of 645771127 is about 25412.0272115390. The cubic root of 645771127 is about 864.3564447024.

The spelling of 645771127 in words is "six hundred forty-five million, seven hundred seventy-one thousand, one hundred twenty-seven".