20806277781 has 64 divisors (see below), whose sum is σ = 30951161856. Its totient is φ = 12373171200.

The previous prime is 20806277777. The next prime is 20806277801. The reversal of 20806277781 is 18777260802.

It is a happy number.

It is not a de Polignac number, because 20806277781 - 2² = 20806277777 is a prime.

It is a super-2 number, since 2×20806277781² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20806277781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20806277711) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 42723120 + ... + 42723606.

It is an arithmetic number, because the mean of its divisors is an integer number (483611904).

Almost surely, 2^20806277781 is an apocalyptic number.

It is an amenable number.

20806277781 is a deficient number, since it is larger than the sum of its proper divisors (10144884075).

20806277781 is a wasteful number, since it uses less digits than its factorization.

20806277781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1042.

The product of its (nonzero) digits is 526848, while the sum is 48.

The spelling of 20806277781 in words is "twenty billion, eight hundred six million, two hundred seventy-seven thousand, seven hundred eighty-one".