645611553 has 20 divisors (see below), whose sum is σ = 966130308. Its totient is φ = 429649920.

The previous prime is 645611513. The next prime is 645611569. The reversal of 645611553 is 355116546.

645611553 is a `hidden beast` number, since 6 + 45 + 61 + 1 + 553 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 230796864 + 414814689 = 15192^2 + 20367^2 .

It is not a de Polignac number, because 645611553 - 2⁹ = 645611041 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645611513) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 41313 + ... + 54753.

Almost surely, 2^645611553 is an apocalyptic number.

It is an amenable number.

645611553 is a deficient number, since it is larger than the sum of its proper divisors (320518755).

645611553 is a wasteful number, since it uses less digits than its factorization.

645611553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14046 (or 14037 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The square root of 645611553 is about 25408.8872837832. The cubic root of 645611553 is about 864.2852429138.

The spelling of 645611553 in words is "six hundred forty-five million, six hundred eleven thousand, five hundred fifty-three".