102815981 has 2 divisors, whose sum is σ = 102815982. Its totient is φ = 102815980.

The previous prime is 102815971. The next prime is 102816013. The reversal of 102815981 is 189518201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 102191881 + 624100 = 10109^2 + 790^2 .

It is an emirp because it is prime and its reverse (189518201) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 102815981 - 2⁶ = 102815917 is a prime.

It is a super-2 number, since 2×102815981² = 21142251897984722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (102815971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 51407990 + 51407991.

It is an arithmetic number, because the mean of its divisors is an integer number (51407991).

Almost surely, 2^102815981 is an apocalyptic number.

It is an amenable number.

102815981 is a deficient number, since it is larger than the sum of its proper divisors (1).

102815981 is an equidigital number, since it uses as much as digits as its factorization.

102815981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 35.

The square root of 102815981 is about 10139.8215467532. The cubic root of 102815981 is about 468.4754904493.

The spelling of 102815981 in words is "one hundred two million, eight hundred fifteen thousand, nine hundred eighty-one".