20815946861 has 8 divisors (see below), whose sum is σ = 21615760824. Its totient is φ = 20030042880.

The previous prime is 20815946857. The next prime is 20815946897. The reversal of 20815946861 is 16864951802.

It can be written as a sum of positive squares in 4 ways, for example, as 2402500 + 20813544361 = 1550^2 + 144269^2 .

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 20815946861 - 2² = 20815946857 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20815948861) 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, 3474446 + ... + 3480431.

It is an arithmetic number, because the mean of its divisors is an integer number (2701970103).

Almost surely, 2^20815946861 is an apocalyptic number.

It is an amenable number.

20815946861 is a deficient number, since it is larger than the sum of its proper divisors (799813963).

20815946861 is an equidigital number, since it uses as much as digits as its factorization.

20815946861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6954991.

The product of its (nonzero) digits is 829440, while the sum is 50.

The spelling of 20815946861 in words is "twenty billion, eight hundred fifteen million, nine hundred forty-six thousand, eight hundred sixty-one".