20813777081 has 8 divisors (see below), whose sum is σ = 20877553224. Its totient is φ = 20750060800.

The previous prime is 20813777077. The next prime is 20813777111. The reversal of 20813777081 is 18077731802.

It can be written as a sum of positive squares in 4 ways, for example, as 3851319481 + 16962457600 = 62059^2 + 130240^2 .

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 20813777081 - 2² = 20813777077 is a prime.

It is a super-2 number, since 2×20813777081² (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 (20813777011) 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, 738851 + ... + 766503.

It is an arithmetic number, because the mean of its divisors is an integer number (2609694153).

Almost surely, 2^20813777081 is an apocalyptic number.

It is an amenable number.

20813777081 is a deficient number, since it is larger than the sum of its proper divisors (63776143).

20813777081 is a wasteful number, since it uses less digits than its factorization.

20813777081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29931.

The product of its (nonzero) digits is 131712, while the sum is 44.

The spelling of 20813777081 in words is "twenty billion, eight hundred thirteen million, seven hundred seventy-seven thousand, eighty-one".