81763581 has 4 divisors (see below), whose sum is σ = 109018112. Its totient is φ = 54509052.

The previous prime is 81763567. The next prime is 81763589. The reversal of 81763581 is 18536718.

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.

It is not a de Polignac number, because 81763581 - 2⁷ = 81763453 is a prime.

It is a super-2 number, since 2×81763581² = 13370566355887122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81763589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13627261 + ... + 13627266.

It is an arithmetic number, because the mean of its divisors is an integer number (27254528).

Almost surely, 2^81763581 is an apocalyptic number.

It is an amenable number.

81763581 is a deficient number, since it is larger than the sum of its proper divisors (27254531).

81763581 is a wasteful number, since it uses less digits than its factorization.

81763581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27254530.

The product of its digits is 40320, while the sum is 39.

The square root of 81763581 is about 9042.3216598394. The cubic root of 81763581 is about 434.0302190374.

The spelling of 81763581 in words is "eighty-one million, seven hundred sixty-three thousand, five hundred eighty-one".