81403680 has 48 divisors (see below), whose sum is σ = 256423104. Its totient is φ = 21707520.

The previous prime is 81403643. The next prime is 81403703. The reversal of 81403680 is 8630418.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84316 + ... + 85275.

It is an arithmetic number, because the mean of its divisors is an integer number (5342148).

Almost surely, 2^81403680 is an apocalyptic number.

81403680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81403680 is an abundant number, since it is smaller than the sum of its proper divisors (175019424).

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

81403680 is a wasteful number, since it uses less digits than its factorization.

81403680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169609 (or 169601 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 81403680 is about 9022.3987941124. The cubic root of 81403680 is about 433.3924547868.

The spelling of 81403680 in words is "eighty-one million, four hundred three thousand, six hundred eighty".