81841616 has 20 divisors (see below), whose sum is σ = 160205892. Its totient is φ = 40498176.

The previous prime is 81841609. The next prime is 81841633. The reversal of 81841616 is 61614818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 27081616 + 54760000 = 5204^2 + 7400^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24815 + ... + 27918.

Almost surely, 2^81841616 is an apocalyptic number.

It is an amenable number.

81841616 is a deficient number, since it is larger than the sum of its proper divisors (78364276).

81841616 is a wasteful number, since it uses less digits than its factorization.

81841616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52838 (or 52832 counting only the distinct ones).

The product of its digits is 9216, while the sum is 35.

The square root of 81841616 is about 9046.6356177310. The cubic root of 81841616 is about 434.1682543273.

The spelling of 81841616 in words is "eighty-one million, eight hundred forty-one thousand, six hundred sixteen".