645140890 has 16 divisors (see below), whose sum is σ = 1161543240. Its totient is φ = 257992000.

The previous prime is 645140887. The next prime is 645140921. The reversal of 645140890 is 98041546.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 161976529 + 483164361 = 12727^2 + 21981^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71640 + ... + 80140.

Almost surely, 2^645140890 is an apocalyptic number.

645140890 is a deficient number, since it is larger than the sum of its proper divisors (516402350).

645140890 is a wasteful number, since it uses less digits than its factorization.

645140890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16097.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 645140890 is about 25399.6238161119. The cubic root of 645140890 is about 864.0751651071.

The spelling of 645140890 in words is "six hundred forty-five million, one hundred forty thousand, eight hundred ninety".