81663769 has 16 divisors (see below), whose sum is σ = 91570176. Its totient is φ = 72192400.

The previous prime is 81663763. The next prime is 81663779. The reversal of 81663769 is 96736618.

It is a cyclic number.

It is not a de Polignac number, because 81663769 - 2⁵ = 81663737 is a prime.

It is a super-3 number, since 3×81663769³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81663763) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 98334 + ... + 99160.

It is an arithmetic number, because the mean of its divisors is an integer number (5723136).

Almost surely, 2^81663769 is an apocalyptic number.

It is an amenable number.

81663769 is a deficient number, since it is larger than the sum of its proper divisors (9906407).

81663769 is a wasteful number, since it uses less digits than its factorization.

81663769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1076.

The product of its digits is 326592, while the sum is 46.

The square root of 81663769 is about 9036.8008166607. The cubic root of 81663769 is about 433.8535345701.

It can be divided in two parts, 8166 and 3769, that added together give a triangular number (11935 = T₁₅₄).

The spelling of 81663769 in words is "eighty-one million, six hundred sixty-three thousand, seven hundred sixty-nine".