645053553 has 12 divisors (see below), whose sum is σ = 980783440. Its totient is φ = 407402136.

The previous prime is 645053551. The next prime is 645053567. The reversal of 645053553 is 355350546.

645053553 is a `hidden beast` number, since 6 + 4 + 50 + 53 + 553 = 666.

It is not a de Polignac number, because 645053553 - 2¹ = 645053551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645053551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1885951 + ... + 1886292.

Almost surely, 2^645053553 is an apocalyptic number.

It is an amenable number.

645053553 is a deficient number, since it is larger than the sum of its proper divisors (335729887).

645053553 is a wasteful number, since it uses less digits than its factorization.

645053553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3772268 (or 3772265 counting only the distinct ones).

The product of its (nonzero) digits is 135000, while the sum is 36.

The square root of 645053553 is about 25397.9045001748. The cubic root of 645053553 is about 864.0361714859.

The spelling of 645053553 in words is "six hundred forty-five million, fifty-three thousand, five hundred fifty-three".