815661653 has 2 divisors, whose sum is σ = 815661654. Its totient is φ = 815661652.

The previous prime is 815661601. The next prime is 815661661. The reversal of 815661653 is 356166518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 469068964 + 346592689 = 21658^2 + 18617^2 .

It is a cyclic number.

It is not a de Polignac number, because 815661653 - 2²⁰ = 814613077 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 815661653.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (815661053) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407830826 + 407830827.

It is an arithmetic number, because the mean of its divisors is an integer number (407830827).

Almost surely, 2^815661653 is an apocalyptic number.

It is an amenable number.

815661653 is a deficient number, since it is larger than the sum of its proper divisors (1).

815661653 is an equidigital number, since it uses as much as digits as its factorization.

815661653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129600, while the sum is 41.

The square root of 815661653 is about 28559.7908430717. The cubic root of 815661653 is about 934.3365719001.

The spelling of 815661653 in words is "eight hundred fifteen million, six hundred sixty-one thousand, six hundred fifty-three".