81417840 has 80 divisors (see below), whose sum is σ = 288457728. Its totient is φ = 18609408.

The previous prime is 81417839. The next prime is 81417883. The reversal of 81417840 is 4871418.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 22552 + ... + 25911.

Almost surely, 2^81417840 is an apocalyptic number.

81417840 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81417840 is an abundant number, since it is smaller than the sum of its proper divisors (207039888).

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

81417840 is a wasteful number, since it uses less digits than its factorization.

81417840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48486 (or 48480 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 33.

The square root of 81417840 is about 9023.1834736971. The cubic root of 81417840 is about 433.4175825672.

The spelling of 81417840 in words is "eighty-one million, four hundred seventeen thousand, eight hundred forty".