102815781201 has 27 divisors (see below), whose sum is σ = 172769804571. Its totient is φ = 58748027184.

The previous prime is 102815781191. The next prime is 102815781241. The reversal of 102815781201 is 102187518201.

The square root of 102815781201 is 320649.

It is a perfect power (a square), and thus also a powerful number.

102815781201 is a `hidden beast` number, since 1 + 0 + 2 + 81 + 578 + 1 + 2 + 0 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 46504491201 + 56311290000 = 215649^2 + 237300^2 .

It is not a de Polignac number, because 102815781201 - 2²¹ = 102813684049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (102815781241) 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 in 26 ways as a sum of consecutive naturals, for example, 6725995 + ... + 6741263.

Almost surely, 2^102815781201 is an apocalyptic number.

102815781201 is the 320649-th square number.

102815781201 is the 160325-th centered octagonal number.

It is an amenable number.

102815781201 is a deficient number, since it is larger than the sum of its proper divisors (69954023370).

102815781201 is an frugal number, since it uses more digits than its factorization.

102815781201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30558 (or 15279 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 36.

Multiplying 102815781201 by its sum of digits (36), we get a square (3701368123236 = 1923894²).

The spelling of 102815781201 in words is "one hundred two billion, eight hundred fifteen million, seven hundred eighty-one thousand, two hundred one".