81261369 has 24 divisors (see below), whose sum is σ = 139980672. Its totient is φ = 44415360.

The previous prime is 81261329. The next prime is 81261379. The reversal of 81261369 is 96316218.

It is not a de Polignac number, because 81261369 - 2⁹ = 81260857 is a prime.

It is a super-2 number, since 2×81261369² = 13206820183508322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81261329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26592 + ... + 29489.

It is an arithmetic number, because the mean of its divisors is an integer number (5832528).

Almost surely, 2^81261369 is an apocalyptic number.

It is an amenable number.

81261369 is a deficient number, since it is larger than the sum of its proper divisors (58719303).

81261369 is a wasteful number, since it uses less digits than its factorization.

81261369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56117 (or 56114 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 81261369 is about 9014.5088052539. The cubic root of 81261369 is about 433.1397533127.

The spelling of 81261369 in words is "eighty-one million, two hundred sixty-one thousand, three hundred sixty-nine".