81496720 has 20 divisors (see below), whose sum is σ = 189480060. Its totient is φ = 32598656.

The previous prime is 81496717. The next prime is 81496729. The reversal of 81496720 is 2769418.

It can be written as a sum of positive squares in 2 ways, for example, as 9314704 + 72182016 = 3052^2 + 8496^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 81496720.

It is not an unprimeable number, because it can be changed into a prime (81496729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 509275 + ... + 509434.

It is an arithmetic number, because the mean of its divisors is an integer number (9474003).

Almost surely, 2^81496720 is an apocalyptic number.

81496720 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81496720 is an abundant number, since it is smaller than the sum of its proper divisors (107983340).

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

81496720 is a wasteful number, since it uses less digits than its factorization.

81496720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018722 (or 1018716 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 81496720 is about 9027.5533784077. The cubic root of 81496720 is about 433.5575066267.

The spelling of 81496720 in words is "eighty-one million, four hundred ninety-six thousand, seven hundred twenty".