640200081 has 4 divisors (see below), whose sum is σ = 853600112. Its totient is φ = 426800052.

The previous prime is 640200049. The next prime is 640200089. The reversal of 640200081 is 180002046.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 640200081 - 2⁵ = 640200049 is a prime.

It is a super-2 number, since 2×640200081² = 819712287424813122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640200089) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 106700011 + ... + 106700016.

It is an arithmetic number, because the mean of its divisors is an integer number (213400028).

Almost surely, 2^640200081 is an apocalyptic number.

It is an amenable number.

640200081 is a deficient number, since it is larger than the sum of its proper divisors (213400031).

640200081 is a wasteful number, since it uses less digits than its factorization.

640200081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213400030.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 640200081 is about 25302.1754203072. The cubic root of 640200081 is about 861.8636711241.

The spelling of 640200081 in words is "six hundred forty million, two hundred thousand, eighty-one".