811388861 has 2 divisors, whose sum is σ = 811388862. Its totient is φ = 811388860.

The previous prime is 811388813. The next prime is 811388951. The reversal of 811388861 is 168883118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 780140761 + 31248100 = 27931^2 + 5590^2 .

It is a cyclic number.

It is not a de Polignac number, because 811388861 - 2¹⁴ = 811372477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (811388561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405694430 + 405694431.

It is an arithmetic number, because the mean of its divisors is an integer number (405694431).

Almost surely, 2^811388861 is an apocalyptic number.

It is an amenable number.

811388861 is a deficient number, since it is larger than the sum of its proper divisors (1).

811388861 is an equidigital number, since it uses as much as digits as its factorization.

811388861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 73728, while the sum is 44.

The square root of 811388861 is about 28484.8882918645. Note that the first 3 decimals coincide. The cubic root of 811388861 is about 932.7022270788.

The spelling of 811388861 in words is "eight hundred eleven million, three hundred eighty-eight thousand, eight hundred sixty-one".