81652621 has 2 divisors, whose sum is σ = 81652622. Its totient is φ = 81652620.

The previous prime is 81652619. The next prime is 81652643. The reversal of 81652621 is 12625618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41139396 + 40513225 = 6414^2 + 6365^2 .

It is a cyclic number.

It is not a de Polignac number, because 81652621 - 2¹ = 81652619 is a prime.

It is a super-4 number, since 4×81652621⁴ (a number of 33 digits) contains 4444 as substring.

Together with 81652619, it forms a pair of twin primes.

It is equal to p_4760329 and since 81652621 and 4760329 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81652651) 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, 40826310 + 40826311.

It is an arithmetic number, because the mean of its divisors is an integer number (40826311).

Almost surely, 2^81652621 is an apocalyptic number.

It is an amenable number.

81652621 is a deficient number, since it is larger than the sum of its proper divisors (1).

81652621 is an equidigital number, since it uses as much as digits as its factorization.

81652621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 31.

The square root of 81652621 is about 9036.1839844040. The cubic root of 81652621 is about 433.8337917500.

The spelling of 81652621 in words is "eighty-one million, six hundred fifty-two thousand, six hundred twenty-one".