640656101 has 8 divisors (see below), whose sum is σ = 681257304. Its totient is φ = 600378880.

The previous prime is 640656089. The next prime is 640656113. The reversal of 640656101 is 101656046.

It is an interprime number because it is at equal distance from previous prime (640656089) and next prime (640656113).

It can be written as a sum of positive squares in 4 ways, for example, as 35988001 + 604668100 = 5999^2 + 24590^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640656101 - 2¹⁴ = 640639717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640656131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76910 + ... + 84831.

It is an arithmetic number, because the mean of its divisors is an integer number (85157163).

Almost surely, 2^640656101 is an apocalyptic number.

It is an amenable number.

640656101 is a deficient number, since it is larger than the sum of its proper divisors (40601203).

640656101 is a wasteful number, since it uses less digits than its factorization.

640656101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161991.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 640656101 is about 25311.1852942528. The cubic root of 640656101 is about 862.0682601795.

The spelling of 640656101 in words is "six hundred forty million, six hundred fifty-six thousand, one hundred one".