81144657 has 36 divisors (see below), whose sum is σ = 129778740. Its totient is φ = 48818880.

The previous prime is 81144641. The next prime is 81144677. The reversal of 81144657 is 75644118.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 9217296 + 71927361 = 3036^2 + 8481^2 .

It is not a de Polignac number, because 81144657 - 2⁴ = 81144641 is a prime.

Its product of digits (26880) is a multiple of the sum of its prime divisors (560).

It is not an unprimeable number, because it can be changed into a prime (81144677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 292803 + ... + 293079.

It is an arithmetic number, because the mean of its divisors is an integer number (3604965).

Almost surely, 2^81144657 is an apocalyptic number.

It is an amenable number.

81144657 is a deficient number, since it is larger than the sum of its proper divisors (48634083).

81144657 is a wasteful number, since it uses less digits than its factorization.

81144657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574 (or 560 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 81144657 is about 9008.0329151264. The cubic root of 81144657 is about 432.9322876621.

The spelling of 81144657 in words is "eighty-one million, one hundred forty-four thousand, six hundred fifty-seven".