20709701857 has 8 divisors (see below), whose sum is σ = 22532682536. Its totient is φ = 18919567872.

The previous prime is 20709701851. The next prime is 20709701861. The reversal of 20709701857 is 75810790702.

It can be written as a sum of positive squares in 4 ways, for example, as 242393761 + 20467308096 = 15569^2 + 143064^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20709701857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20709701851) 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 in 7 ways as a sum of consecutive naturals, for example, 8210358 + ... + 8212879.

It is an arithmetic number, because the mean of its divisors is an integer number (2816585317).

Almost surely, 2^20709701857 is an apocalyptic number.

It is an amenable number.

20709701857 is a deficient number, since it is larger than the sum of its proper divisors (1822980679).

20709701857 is a wasteful number, since it uses less digits than its factorization.

20709701857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16423347.

The product of its (nonzero) digits is 246960, while the sum is 46.

The spelling of 20709701857 in words is "twenty billion, seven hundred nine million, seven hundred one thousand, eight hundred fifty-seven".