645624890 has 8 divisors (see below), whose sum is σ = 1162124820. Its totient is φ = 258249952.

The previous prime is 645624887. The next prime is 645624899. The reversal of 645624890 is 98426546.

It can be written as a sum of positive squares in 2 ways, for example, as 645312409 + 312481 = 25403^2 + 559^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (645624899) 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 3 ways as a sum of consecutive naturals, for example, 32281235 + ... + 32281254.

Almost surely, 2^645624890 is an apocalyptic number.

645624890 is a deficient number, since it is larger than the sum of its proper divisors (516499930).

645624890 is a wasteful number, since it uses less digits than its factorization.

645624890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64562496.

The product of its (nonzero) digits is 414720, while the sum is 44.

The square root of 645624890 is about 25409.1497299693. The cubic root of 645624890 is about 864.2911943216.

The spelling of 645624890 in words is "six hundred forty-five million, six hundred twenty-four thousand, eight hundred ninety".