815971513849 has 2 divisors, whose sum is σ = 815971513850. Its totient is φ = 815971513848.

The previous prime is 815971513817. The next prime is 815971513853. The reversal of 815971513849 is 948315179518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 563070144400 + 252901369449 = 750380^2 + 502893^2 .

It is a cyclic number.

It is not a de Polignac number, because 815971513849 - 2⁵ = 815971513817 is a prime.

It is a super-2 number, since 2×815971513849² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (815971513859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407985756924 + 407985756925.

It is an arithmetic number, because the mean of its divisors is an integer number (407985756925).

Almost surely, 2^815971513849 is an apocalyptic number.

It is an amenable number.

815971513849 is a deficient number, since it is larger than the sum of its proper divisors (1).

815971513849 is an equidigital number, since it uses as much as digits as its factorization.

815971513849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10886400, while the sum is 61.

The spelling of 815971513849 in words is "eight hundred fifteen billion, nine hundred seventy-one million, five hundred thirteen thousand, eight hundred forty-nine".