81863544 has 32 divisors (see below), whose sum is σ = 233896320. Its totient is φ = 23389536.

The previous prime is 81863543. The next prime is 81863563. The reversal of 81863544 is 44536818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81863543) 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, 243474 + ... + 243809.

It is an arithmetic number, because the mean of its divisors is an integer number (7309260).

Almost surely, 2^81863544 is an apocalyptic number.

81863544 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81863544 is an abundant number, since it is smaller than the sum of its proper divisors (152032776).

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

81863544 is a wasteful number, since it uses less digits than its factorization.

81863544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 487299 (or 487295 counting only the distinct ones).

The product of its digits is 92160, while the sum is 39.

The square root of 81863544 is about 9047.8474788206. The cubic root of 81863544 is about 434.2070267425.

The spelling of 81863544 in words is "eighty-one million, eight hundred sixty-three thousand, five hundred forty-four".