81263505 has 8 divisors (see below), whose sum is σ = 130021632. Its totient is φ = 43340528.

The previous prime is 81263491. The next prime is 81263521. The reversal of 81263505 is 50536218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81263505 - 2¹¹ = 81261457 is a prime.

It is a super-3 number, since 3×81263505³ (a number of 25 digits) contains 333 as substring.

It is a Curzon number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2708769 + ... + 2708798.

It is an arithmetic number, because the mean of its divisors is an integer number (16252704).

Almost surely, 2^81263505 is an apocalyptic number.

It is an amenable number.

81263505 is a deficient number, since it is larger than the sum of its proper divisors (48758127).

81263505 is a wasteful number, since it uses less digits than its factorization.

81263505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5417575.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 81263505 is about 9014.6272801486. The cubic root of 81263505 is about 433.1435483854.

The spelling of 81263505 in words is "eighty-one million, two hundred sixty-three thousand, five hundred five".