645632778 has 16 divisors (see below), whose sum is σ = 1475732160. Its totient is φ = 184466496.

The previous prime is 645632761. The next prime is 645632797. The reversal of 645632778 is 877236546.

645632778 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×645632778³ (a number of 27 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7686063 + ... + 7686146.

It is an arithmetic number, because the mean of its divisors is an integer number (92233260).

Almost surely, 2^645632778 is an apocalyptic number.

645632778 is an abundant number, since it is smaller than the sum of its proper divisors (830099382).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645632778 is a wasteful number, since it uses less digits than its factorization.

645632778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15372221.

The product of its digits is 1693440, while the sum is 48.

The square root of 645632778 is about 25409.3049491717. The cubic root of 645632778 is about 864.2947141679.

The spelling of 645632778 in words is "six hundred forty-five million, six hundred thirty-two thousand, seven hundred seventy-eight".