81230021 has 4 divisors (see below), whose sum is σ = 81684000. Its totient is φ = 80776044.

The previous prime is 81230011. The next prime is 81230041. The reversal of 81230021 is 12003218.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12003218 = 2 ⋅6001609.

It is a cyclic number.

It is not a de Polignac number, because 81230021 - 2¹⁰ = 81228997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81230011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 226721 + ... + 227078.

It is an arithmetic number, because the mean of its divisors is an integer number (20421000).

Almost surely, 2^81230021 is an apocalyptic number.

It is an amenable number.

81230021 is a deficient number, since it is larger than the sum of its proper divisors (453979).

81230021 is a wasteful number, since it uses less digits than its factorization.

81230021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 453978.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 81230021 is about 9012.7698850021. The cubic root of 81230021 is about 433.0840490606.

Adding to 81230021 its reverse (12003218), we get a palindrome (93233239).

The spelling of 81230021 in words is "eighty-one million, two hundred thirty thousand, twenty-one".