81862640 has 40 divisors (see below), whose sum is σ = 200351760. Its totient is φ = 31021056.

The previous prime is 81862619. The next prime is 81862643. The reversal of 81862640 is 4626818.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 81862640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81862643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25409 + ... + 28448.

It is an arithmetic number, because the mean of its divisors is an integer number (5008794).

Almost surely, 2^81862640 is an apocalyptic number.

81862640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81862640 is an abundant number, since it is smaller than the sum of its proper divisors (118489120).

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

81862640 is a wasteful number, since it uses less digits than its factorization.

81862640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53889 (or 53883 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 81862640 is about 9047.7975220492. The cubic root of 81862640 is about 434.2054284543.

The spelling of 81862640 in words is "eighty-one million, eight hundred sixty-two thousand, six hundred forty".