645504399 has 24 divisors (see below), whose sum is σ = 996851232. Its totient is φ = 401080320.

The previous prime is 645504397. The next prime is 645504469. The reversal of 645504399 is 993405546.

645504399 is a `hidden beast` number, since 6 + 4 + 550 + 4 + 3 + 99 = 666.

It is not a de Polignac number, because 645504399 - 2¹ = 645504397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645504397) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4722 + ... + 36239.

It is an arithmetic number, because the mean of its divisors is an integer number (41535468).

Almost surely, 2^645504399 is an apocalyptic number.

645504399 is a deficient number, since it is larger than the sum of its proper divisors (351346833).

645504399 is a wasteful number, since it uses less digits than its factorization.

645504399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41087 (or 41084 counting only the distinct ones).

The product of its (nonzero) digits is 583200, while the sum is 45.

The square root of 645504399 is about 25406.7786033570. The cubic root of 645504399 is about 864.2374243018.

The spelling of 645504399 in words is "six hundred forty-five million, five hundred four thousand, three hundred ninety-nine".