645204215 has 4 divisors (see below), whose sum is σ = 774245064. Its totient is φ = 516163368.

The previous prime is 645204191. The next prime is 645204221. The reversal of 645204215 is 512402546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645204215 - 2¹⁸ = 644942071 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64520417 + ... + 64520426.

It is an arithmetic number, because the mean of its divisors is an integer number (193561266).

Almost surely, 2^645204215 is an apocalyptic number.

645204215 is a deficient number, since it is larger than the sum of its proper divisors (129040849).

645204215 is a wasteful number, since it uses less digits than its factorization.

645204215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129040848.

The product of its (nonzero) digits is 9600, while the sum is 29.

The square root of 645204215 is about 25400.8703591038. The cubic root of 645204215 is about 864.1034358153.

The spelling of 645204215 in words is "six hundred forty-five million, two hundred four thousand, two hundred fifteen".