20656820657 has 8 divisors (see below), whose sum is σ = 22535760000. Its totient is φ = 18778055760.

The previous prime is 20656820629. The next prime is 20656820659. The reversal of 20656820657 is 75602865602.

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 20656820657 - 2⁶ = 20656820593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20656820659) 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, 402008 + ... + 450470.

It is an arithmetic number, because the mean of its divisors is an integer number (2816970000).

Almost surely, 2^20656820657 is an apocalyptic number.

It is an amenable number.

20656820657 is a deficient number, since it is larger than the sum of its proper divisors (1878939343).

20656820657 is a wasteful number, since it uses less digits than its factorization.

20656820657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87223.

The product of its (nonzero) digits is 1209600, while the sum is 47.

The spelling of 20656820657 in words is "twenty billion, six hundred fifty-six million, eight hundred twenty thousand, six hundred fifty-seven".