20805737818 has 4 divisors (see below), whose sum is σ = 31208606730. Its totient is φ = 10402868908.

The previous prime is 20805737803. The next prime is 20805737851. The reversal of 20805737818 is 81873750802.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19427620689 + 1378117129 = 139383^2 + 37123^2 .

It is a super-2 number, since 2×20805737818² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5201434453 + ... + 5201434456.

Almost surely, 2^20805737818 is an apocalyptic number.

20805737818 is a deficient number, since it is larger than the sum of its proper divisors (10402868912).

20805737818 is a wasteful number, since it uses less digits than its factorization.

20805737818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10402868911.

The product of its (nonzero) digits is 752640, while the sum is 49.

The spelling of 20805737818 in words is "twenty billion, eight hundred five million, seven hundred thirty-seven thousand, eight hundred eighteen".