645506399 has 8 divisors (see below), whose sum is σ = 683280000. Its totient is φ = 608112792.

The previous prime is 645506387. The next prime is 645506401. The reversal of 645506399 is 993605546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645506399 - 2⁴ = 645506383 is a prime.

It is a super-2 number, since 2×645506399² = 833357022299894402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645500399) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91499 + ... + 98300.

It is an arithmetic number, because the mean of its divisors is an integer number (85410000).

Almost surely, 2^645506399 is an apocalyptic number.

645506399 is a deficient number, since it is larger than the sum of its proper divisors (37773601).

645506399 is a wasteful number, since it uses less digits than its factorization.

645506399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189997.

The product of its (nonzero) digits is 874800, while the sum is 47.

The square root of 645506399 is about 25406.8179629012. The cubic root of 645506399 is about 864.2383168715.

The spelling of 645506399 in words is "six hundred forty-five million, five hundred six thousand, three hundred ninety-nine".