20781732977 has 8 divisors (see below), whose sum is σ = 22005982152. Its totient is φ = 19557683200.

The previous prime is 20781732953. The next prime is 20781733001. The reversal of 20781732977 is 77923718702.

It is an interprime number because it is at equal distance from previous prime (20781732953) and next prime (20781733001).

It can be written as a sum of positive squares in 4 ways, for example, as 2010266896 + 18771466081 = 44836^2 + 137009^2 .

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 20781732977 - 2¹⁶ = 20781667441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20781732077) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 200777 + ... + 286137.

It is an arithmetic number, because the mean of its divisors is an integer number (2750747769).

Almost surely, 2^20781732977 is an apocalyptic number.

It is an amenable number.

20781732977 is a deficient number, since it is larger than the sum of its proper divisors (1224249175).

20781732977 is a wasteful number, since it uses less digits than its factorization.

20781732977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99699.

The product of its (nonzero) digits is 2074464, while the sum is 53.

The spelling of 20781732977 in words is "twenty billion, seven hundred eighty-one million, seven hundred thirty-two thousand, nine hundred seventy-seven".