20156843817 has 32 divisors (see below), whose sum is σ = 33371291520. Its totient is φ = 11918304000.

The previous prime is 20156843783. The next prime is 20156843821. The reversal of 20156843817 is 71834865102.

20156843817 is a `hidden beast` number, since 2 + 0 + 1 + 568 + 4 + 3 + 81 + 7 = 666.

It is not a de Polignac number, because 20156843817 - 2¹⁰ = 20156842793 is a prime.

It is a super-2 number, since 2×20156843817² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20156843417) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 815484 + ... + 839837.

It is an arithmetic number, because the mean of its divisors is an integer number (1042852860).

Almost surely, 2^20156843817 is an apocalyptic number.

20156843817 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

20156843817 is a deficient number, since it is larger than the sum of its proper divisors (13214447703).

20156843817 is a wasteful number, since it uses less digits than its factorization.

20156843817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1655382 (or 1655376 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The spelling of 20156843817 in words is "twenty billion, one hundred fifty-six million, eight hundred forty-three thousand, eight hundred seventeen".