645842290 has 16 divisors (see below), whose sum is σ = 1162909080. Its totient is φ = 258249600.

The previous prime is 645842213. The next prime is 645842293. The reversal of 645842290 is 92248546.

It can be written as a sum of positive squares in 4 ways, for example, as 167676601 + 478165689 = 12949^2 + 21867^2 .

It is a super-2 number, since 2×645842290² = 834224527104888200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (645842293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26140 + ... + 44440.

Almost surely, 2^645842290 is an apocalyptic number.

645842290 is a deficient number, since it is larger than the sum of its proper divisors (517066790).

645842290 is a wasteful number, since it uses less digits than its factorization.

645842290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21837.

The product of its (nonzero) digits is 138240, while the sum is 40.

The square root of 645842290 is about 25413.4273564193. The cubic root of 645842290 is about 864.3881937932.

The spelling of 645842290 in words is "six hundred forty-five million, eight hundred forty-two thousand, two hundred ninety".