645779207 has 4 divisors (see below), whose sum is σ = 646122960. Its totient is φ = 645435456.

The previous prime is 645779161. The next prime is 645779219. The reversal of 645779207 is 702977546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 702977546 = 2 ⋅351488773.

It is a cyclic number.

It is not a de Polignac number, because 645779207 - 2⁶ = 645779143 is a prime.

It is a super-3 number, since 3×645779207³ (a number of 27 digits) contains 333 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 (645779227) 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, 169043 + ... + 172820.

It is an arithmetic number, because the mean of its divisors is an integer number (161530740).

Almost surely, 2^645779207 is an apocalyptic number.

645779207 is a deficient number, since it is larger than the sum of its proper divisors (343753).

645779207 is a wasteful number, since it uses less digits than its factorization.

645779207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343752.

The product of its (nonzero) digits is 740880, while the sum is 47.

The square root of 645779207 is about 25412.1861908809. The cubic root of 645779207 is about 864.3600496798.

The spelling of 645779207 in words is "six hundred forty-five million, seven hundred seventy-nine thousand, two hundred seven".