640660361221 has 8 divisors (see below), whose sum is σ = 646936020224. Its totient is φ = 634385772720.

The previous prime is 640660361219. The next prime is 640660361249. The reversal of 640660361221 is 122163066046.

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 640660361221 - 2¹ = 640660361219 is a prime.

It is a super-2 number, since 2×640660361221² (a number of 24 digits) 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 (640660361261) 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, 962731 + ... + 1485991.

It is an arithmetic number, because the mean of its divisors is an integer number (80867002528).

Almost surely, 2^640660361221 is an apocalyptic number.

It is an amenable number.

640660361221 is a deficient number, since it is larger than the sum of its proper divisors (6275659003).

640660361221 is a wasteful number, since it uses less digits than its factorization.

640660361221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535251.

The product of its (nonzero) digits is 62208, while the sum is 37.

The spelling of 640660361221 in words is "six hundred forty billion, six hundred sixty million, three hundred sixty-one thousand, two hundred twenty-one".