811721653 has 2 divisors, whose sum is σ = 811721654. Its totient is φ = 811721652.

The previous prime is 811721611. The next prime is 811721699. The reversal of 811721653 is 356127118.

It is a happy number.

811721653 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 583802244 + 227919409 = 24162^2 + 15097^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-811721653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (811728653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405860826 + 405860827.

It is an arithmetic number, because the mean of its divisors is an integer number (405860827).

Almost surely, 2^811721653 is an apocalyptic number.

It is an amenable number.

811721653 is a deficient number, since it is larger than the sum of its proper divisors (1).

811721653 is an equidigital number, since it uses as much as digits as its factorization.

811721653 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 34.

The square root of 811721653 is about 28490.7292465461. The cubic root of 811721653 is about 932.8297259176.

The spelling of 811721653 in words is "eight hundred eleven million, seven hundred twenty-one thousand, six hundred fifty-three".