640815540919 has 4 divisors (see below), whose sum is σ = 640818535896. Its totient is φ = 640812545944.

The previous prime is 640815540901. The next prime is 640815540941. The reversal of 640815540919 is 919045518046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 919045518046 = 2 ⋅459522759023.

It is a cyclic number.

It is not a de Polignac number, because 640815540919 - 2⁵ = 640815540887 is a prime.

It is a super-3 number, since 3×640815540919³ (a number of 36 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640815540949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1149604 + ... + 1613449.

It is an arithmetic number, because the mean of its divisors is an integer number (160204633974).

Almost surely, 2^640815540919 is an apocalyptic number.

640815540919 is a deficient number, since it is larger than the sum of its proper divisors (2994977).

640815540919 is a wasteful number, since it uses less digits than its factorization.

640815540919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2994976.

The product of its (nonzero) digits is 1555200, while the sum is 52.

The spelling of 640815540919 in words is "six hundred forty billion, eight hundred fifteen million, five hundred forty thousand, nine hundred nineteen".