20707681817 has 4 divisors (see below), whose sum is σ = 20865755856. Its totient is φ = 20549607780.

The previous prime is 20707681783. The next prime is 20707681837. The reversal of 20707681817 is 71818670702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71818670702 = 2 ⋅35909335351.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20707681817 is a prime.

It is a super-2 number, since 2×20707681817² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20707681837) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79036823 + ... + 79037084.

It is an arithmetic number, because the mean of its divisors is an integer number (5216438964).

Almost surely, 2^20707681817 is an apocalyptic number.

It is an amenable number.

20707681817 is a deficient number, since it is larger than the sum of its proper divisors (158074039).

20707681817 is a wasteful number, since it uses less digits than its factorization.

20707681817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158074038.

The product of its (nonzero) digits is 263424, while the sum is 47.

The spelling of 20707681817 in words is "twenty billion, seven hundred seven million, six hundred eighty-one thousand, eight hundred seventeen".