640910109 has 16 divisors (see below), whose sum is σ = 1028026880. Its totient is φ = 346958640.

The previous prime is 640910087. The next prime is 640910117. The reversal of 640910109 is 901019046.

It is not a de Polignac number, because 640910109 - 2⁸ = 640909853 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640910009) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 802747 + ... + 803544.

It is an arithmetic number, because the mean of its divisors is an integer number (64251680).

Almost surely, 2^640910109 is an apocalyptic number.

It is an amenable number.

640910109 is a deficient number, since it is larger than the sum of its proper divisors (387116771).

640910109 is a wasteful number, since it uses less digits than its factorization.

640910109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1606320.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 640910109 is about 25316.2024995851. The cubic root of 640910109 is about 862.1821763669.

The spelling of 640910109 in words is "six hundred forty million, nine hundred ten thousand, one hundred nine".