81503969121 has 15 divisors (see below), whose sum is σ = 121756681123. Its totient is φ = 54334266480.

The previous prime is 81503969089. The next prime is 81503969147. The reversal of 81503969121 is 12196930518.

The square root of 81503969121 is 285489.

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

81503969121 is a `hidden beast` number, since 8 + 150 + 396 + 91 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 2250458721 + 79253510400 = 47439^2 + 281520^2 .

It is not a de Polignac number, because 81503969121 - 2⁵ = 81503969089 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81503969161) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 2553541 + ... + 2585261.

Almost surely, 2^81503969121 is an apocalyptic number.

81503969121 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

81503969121 is the 285489-th square number.

81503969121 is the 142745-th centered octagonal number.

It is an amenable number.

81503969121 is a deficient number, since it is larger than the sum of its proper divisors (40252712002).

81503969121 is an frugal number, since it uses more digits than its factorization.

81503969121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63454 (or 31724 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The spelling of 81503969121 in words is "eighty-one billion, five hundred three million, nine hundred sixty-nine thousand, one hundred twenty-one".