81221026 has 4 divisors (see below), whose sum is σ = 121831542. Its totient is φ = 40610512.

The previous prime is 81221009. The next prime is 81221057. The reversal of 81221026 is 62012218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 62012218 = 2 ⋅31006109.

It can be written as a sum of positive squares in only one way, i.e., 44023225 + 37197801 = 6635^2 + 6099^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 81220988 and 81221006.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20305255 + ... + 20305258.

Almost surely, 2^81221026 is an apocalyptic number.

81221026 is a deficient number, since it is larger than the sum of its proper divisors (40610516).

81221026 is a wasteful number, since it uses less digits than its factorization.

81221026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40610515.

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 81221026 is about 9012.2708570038. The cubic root of 81221026 is about 433.0680626277.

The spelling of 81221026 in words is "eighty-one million, two hundred twenty-one thousand, twenty-six".