20817356665031 has 16 divisors (see below), whose sum is σ = 21765570393600. Its totient is φ = 19872765383328.

The previous prime is 20817356664947. The next prime is 20817356665081. The reversal of 20817356665031 is 13056665371802.

It is not a de Polignac number, because 20817356665031 - 2²² = 20817352470727 is a prime.

It is a super-2 number, since 2×20817356665031² (a number of 27 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 (20817356665081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30477230 + ... + 31152788.

It is an arithmetic number, because the mean of its divisors is an integer number (1360348149600).

Almost surely, 2^{20817356665031} is an apocalyptic number.

20817356665031 is a deficient number, since it is larger than the sum of its proper divisors (948213728569).

20817356665031 is a wasteful number, since it uses less digits than its factorization.

20817356665031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678238.

The product of its (nonzero) digits is 5443200, while the sum is 53.

The spelling of 20817356665031 in words is "twenty trillion, eight hundred seventeen billion, three hundred fifty-six million, six hundred sixty-five thousand, thirty-one".