81931416 has 64 divisors (see below), whose sum is σ = 235526400. Its totient is φ = 23265408.

The previous prime is 81931411. The next prime is 81931427. The reversal of 81931416 is 61413918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81931411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27655 + ... + 30473.

It is an arithmetic number, because the mean of its divisors is an integer number (3680100).

Almost surely, 2^81931416 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81931416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117763200).

81931416 is an abundant number, since it is smaller than the sum of its proper divisors (153594984).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81931416 is a wasteful number, since it uses less digits than its factorization.

81931416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3008 (or 3004 counting only the distinct ones).

The product of its digits is 5184, while the sum is 33.

The square root of 81931416 is about 9051.5974280786. The cubic root of 81931416 is about 434.3269920616.

The spelling of 81931416 in words is "eighty-one million, nine hundred thirty-one thousand, four hundred sixteen".