81744400 has 30 divisors (see below), whose sum is σ = 196391882. Its totient is φ = 32697600.

The previous prime is 81744373. The next prime is 81744407. The reversal of 81744400 is 444718.

It can be written as a sum of positive squares in 3 ways, for example, as 15745024 + 65999376 = 3968^2 + 8124^2 .

It is not an unprimeable number, because it can be changed into a prime (81744407) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 101781 + ... + 102580.

Almost surely, 2^81744400 is an apocalyptic number.

81744400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81744400 is an abundant number, since it is smaller than the sum of its proper divisors (114647482).

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

81744400 is a wasteful number, since it uses less digits than its factorization.

81744400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204379 (or 204368 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 81744400 is about 9041.2609740014. The cubic root of 81744400 is about 433.9962765224.

The spelling of 81744400 in words is "eighty-one million, seven hundred forty-four thousand, four hundred".