20320640656 has 10 divisors (see below), whose sum is σ = 39371241302. Its totient is φ = 10160320320.

The previous prime is 20320640653. The next prime is 20320640713. The reversal of 20320640656 is 65604602302.

It can be written as a sum of positive squares in only one way, i.e., 17848960000 + 2471680656 = 133600^2 + 49716^2 .

It is a super-2 number, since 2×20320640656² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20320640653) 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 as a sum of consecutive naturals, namely, 635020005 + ... + 635020036.

Almost surely, 2^20320640656 is an apocalyptic number.

It is an amenable number.

20320640656 is a deficient number, since it is larger than the sum of its proper divisors (19050600646).

20320640656 is a wasteful number, since it uses less digits than its factorization.

20320640656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1270040049 (or 1270040043 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 34.

The spelling of 20320640656 in words is "twenty billion, three hundred twenty million, six hundred forty thousand, six hundred fifty-six".