81466089172 has 18 divisors (see below), whose sum is σ = 153536124014. Its totient is φ = 37598783520.

The previous prime is 81466089151. The next prime is 81466089179. The reversal of 81466089172 is 27198066418.

It can be written as a sum of positive squares in 3 ways, for example, as 11243209156 + 70222880016 = 106034^2 + 264996^2 .

It is a Harshad number since it is a multiple of its sum of digits (52).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81466089179) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2038422 + ... + 2078002.

Almost surely, 2^81466089172 is an apocalyptic number.

It is an amenable number.

81466089172 is a deficient number, since it is larger than the sum of its proper divisors (72070034842).

81466089172 is an frugal number, since it uses more digits than its factorization.

81466089172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79179 (or 39596 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 52.

Multiplying 81466089172 by its sum of digits (52), we get a square (4236236636944 = 2058212²).

81466089172 divided by its sum of digits (52) gives a square (1566655561 = 39581²).

The spelling of 81466089172 in words is "eighty-one billion, four hundred sixty-six million, eighty-nine thousand, one hundred seventy-two".