81846640 has 20 divisors (see below), whose sum is σ = 190293624. Its totient is φ = 32738624.

The previous prime is 81846637. The next prime is 81846641. The reversal of 81846640 is 4664818.

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 81846640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81846641) 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 3 ways as a sum of consecutive naturals, for example, 511462 + ... + 511621.

Almost surely, 2^81846640 is an apocalyptic number.

81846640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81846640 is an abundant number, since it is smaller than the sum of its proper divisors (108446984).

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

81846640 is a wasteful number, since it uses less digits than its factorization.

81846640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023096 (or 1023090 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 37.

The square root of 81846640 is about 9046.9132857566. The cubic root of 81846640 is about 434.1771382212.

The spelling of 81846640 in words is "eighty-one million, eight hundred forty-six thousand, six hundred forty".