645440010541553 has 4 divisors (see below), whose sum is σ = 645440372696820. Its totient is φ = 645439648386288.

The previous prime is 645440010541453. The next prime is 645440010541607. The reversal of 645440010541553 is 355145010044546.

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

It can be written as a sum of positive squares in 2 ways, for example, as 487719265790689 + 157720744750864 = 22084367^2 + 12558692^2 .

It is a cyclic number.

It is not a de Polignac number, because 645440010541553 - 2²⁰ = 645440009492977 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645440010541498 and 645440010541507.

It is not an unprimeable number, because it can be changed into a prime (645440010541453) 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, 178391018 + ... + 181973171.

It is an arithmetic number, because the mean of its divisors is an integer number (161360093174205).

Almost surely, 2^{645440010541553} is an apocalyptic number.

It is an amenable number.

645440010541553 is a deficient number, since it is larger than the sum of its proper divisors (362155267).

645440010541553 is a wasteful number, since it uses less digits than its factorization.

645440010541553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 362155266.

The product of its (nonzero) digits is 2880000, while the sum is 47.

The spelling of 645440010541553 in words is "six hundred forty-five trillion, four hundred forty billion, ten million, five hundred forty-one thousand, five hundred fifty-three".