645553501 has 4 divisors (see below), whose sum is σ = 645612604. Its totient is φ = 645494400.

The previous prime is 645553483. The next prime is 645553523. The reversal of 645553501 is 105355546.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 226532601 + 419020900 = 15051^2 + 20470^2 .

It is a cyclic number.

It is not a de Polignac number, because 645553501 - 2⁷ = 645553373 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645553901) 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, 7860 + ... + 36781.

It is an arithmetic number, because the mean of its divisors is an integer number (161403151).

Almost surely, 2^645553501 is an apocalyptic number.

It is an amenable number.

645553501 is a deficient number, since it is larger than the sum of its proper divisors (59103).

645553501 is a wasteful number, since it uses less digits than its factorization.

645553501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59102.

The product of its (nonzero) digits is 45000, while the sum is 34.

The square root of 645553501 is about 25407.7449018995. The cubic root of 645553501 is about 864.2593372483.

The spelling of 645553501 in words is "six hundred forty-five million, five hundred fifty-three thousand, five hundred one".