85815656621 has 2 divisors, whose sum is σ = 85815656622. Its totient is φ = 85815656620.

The previous prime is 85815656599. The next prime is 85815656669. The reversal of 85815656621 is 12665651858.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 85339936900 + 475719721 = 292130^2 + 21811^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-85815656621 is a prime.

It is a super-2 number, since 2×85815656621² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (85815656221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42907828310 + 42907828311.

It is an arithmetic number, because the mean of its divisors is an integer number (42907828311).

Almost surely, 2^85815656621 is an apocalyptic number.

It is an amenable number.

85815656621 is a deficient number, since it is larger than the sum of its proper divisors (1).

85815656621 is an equidigital number, since it uses as much as digits as its factorization.

85815656621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456000, while the sum is 53.

The spelling of 85815656621 in words is "eighty-five billion, eight hundred fifteen million, six hundred fifty-six thousand, six hundred twenty-one".