81881250201 has 9 divisors (see below), whose sum is σ = 118274156949. Its totient is φ = 54586927836.

The previous prime is 81881250179. The next prime is 81881250229. The reversal of 81881250201 is 10205218818.

The square root of 81881250201 is 286149.

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

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 81881250201 - 2⁹ = 81881249689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81881250401) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 810756 + ... + 906138.

Almost surely, 2^81881250201 is an apocalyptic number.

81881250201 is the 286149-th square number.

81881250201 is the 143075-th centered octagonal number.

It is an amenable number.

81881250201 is a deficient number, since it is larger than the sum of its proper divisors (36392906748).

81881250201 is an frugal number, since it uses more digits than its factorization.

81881250201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190772 (or 95386 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 36.

Multiplying 81881250201 by its sum of digits (36), we get a square (2947725007236 = 1716894²).

The spelling of 81881250201 in words is "eighty-one billion, eight hundred eighty-one million, two hundred fifty thousand, two hundred one".