81198121 has 3 divisors (see below), whose sum is σ = 81207133. Its totient is φ = 81189110.

The previous prime is 81198113. The next prime is 81198151. The reversal of 81198121 is 12189118.

The square root of 81198121 is 9011.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 81198121 - 2³ = 81198113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81198151) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4506 + ... + 13516.

Almost surely, 2^81198121 is an apocalyptic number.

81198121 is the 9011-st square number.

81198121 is the 4506-th centered octagonal number.

It is an amenable number.

81198121 is a deficient number, since it is larger than the sum of its proper divisors (9012).

81198121 is an frugal number, since it uses more digits than its factorization.

81198121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18022 (or 9011 counting only the distinct ones).

The product of its digits is 1152, while the sum is 31.

The cubic root of 81198121 is about 433.0273492105.

The spelling of 81198121 in words is "eighty-one million, one hundred ninety-eight thousand, one hundred twenty-one".