645520515127 has 4 divisors (see below), whose sum is σ = 645568073856. Its totient is φ = 645472956400.

The previous prime is 645520515121. The next prime is 645520515181. The reversal of 645520515127 is 721515025546.

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 645520515127 - 2⁷ = 645520514999 is a prime.

It is a super-2 number, since 2×645520515127² (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 (645520515121) 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, 23758999 + ... + 23786152.

It is an arithmetic number, because the mean of its divisors is an integer number (161392018464).

Almost surely, 2^645520515127 is an apocalyptic number.

645520515127 is a deficient number, since it is larger than the sum of its proper divisors (47558729).

645520515127 is a wasteful number, since it uses less digits than its factorization.

645520515127 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47558728.

The product of its (nonzero) digits is 420000, while the sum is 43.

The spelling of 645520515127 in words is "six hundred forty-five billion, five hundred twenty million, five hundred fifteen thousand, one hundred twenty-seven".