81144665 has 16 divisors (see below), whose sum is σ = 112000512. Its totient is φ = 55283904.

The previous prime is 81144641. The next prime is 81144677. The reversal of 81144665 is 56644118.

It is a cyclic number.

It is not a de Polignac number, because 81144665 - 2⁶ = 81144601 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1889 + ... + 12878.

It is an arithmetic number, because the mean of its divisors is an integer number (7000032).

Almost surely, 2^81144665 is an apocalyptic number.

It is an amenable number.

81144665 is a deficient number, since it is larger than the sum of its proper divisors (30855847).

81144665 is a wasteful number, since it uses less digits than its factorization.

81144665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14936.

The product of its digits is 23040, while the sum is 35.

The square root of 81144665 is about 9008.0333591745. The cubic root of 81144665 is about 432.9323018896.

The spelling of 81144665 in words is "eighty-one million, one hundred forty-four thousand, six hundred sixty-five".