640120711 has 4 divisors (see below), whose sum is σ = 641717424. Its totient is φ = 638524000.

The previous prime is 640120709. The next prime is 640120717. The reversal of 640120711 is 117021046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 117021046 = 2 ⋅58510523.

It is a cyclic number.

It is not a de Polignac number, because 640120711 - 2¹ = 640120709 is a prime.

It is a super-2 number, since 2×640120711² = 819509049302291042, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640120717) 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, 797755 + ... + 798556.

It is an arithmetic number, because the mean of its divisors is an integer number (160429356).

Almost surely, 2^640120711 is an apocalyptic number.

640120711 is a deficient number, since it is larger than the sum of its proper divisors (1596713).

640120711 is a wasteful number, since it uses less digits than its factorization.

640120711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1596712.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 640120711 is about 25300.6069294790. The cubic root of 640120711 is about 861.8280525997.

Adding to 640120711 its reverse (117021046), we get a palindrome (757141757).

The spelling of 640120711 in words is "six hundred forty million, one hundred twenty thousand, seven hundred eleven".