640656055 has 16 divisors (see below), whose sum is σ = 828473184. Its totient is φ = 472786560.

The previous prime is 640656019. The next prime is 640656061. The reversal of 640656055 is 550656046.

It is not a de Polignac number, because 640656055 - 2¹³ = 640647863 is a prime.

It is a super-3 number, since 3×640656055³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 152037 + ... + 156193.

It is an arithmetic number, because the mean of its divisors is an integer number (51779574).

Almost surely, 2^640656055 is an apocalyptic number.

640656055 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

640656055 is a deficient number, since it is larger than the sum of its proper divisors (187817129).

640656055 is a wasteful number, since it uses less digits than its factorization.

640656055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6546.

The product of its (nonzero) digits is 108000, while the sum is 37.

The square root of 640656055 is about 25311.1843855636. The cubic root of 640656055 is about 862.0682395469.

Subtracting from 640656055 its reverse (550656046), we obtain a palindrome (90000009).

The spelling of 640656055 in words is "six hundred forty million, six hundred fifty-six thousand, fifty-five".