81743440 has 20 divisors (see below), whose sum is σ = 190053684. Its totient is φ = 32697344.

The previous prime is 81743419. The next prime is 81743443. The reversal of 81743440 is 4434718.

It can be written as a sum of positive squares in 2 ways, for example, as 59351616 + 22391824 = 7704^2 + 4732^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81743443) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 510817 + ... + 510976.

Almost surely, 2^81743440 is an apocalyptic number.

81743440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81743440 is an abundant number, since it is smaller than the sum of its proper divisors (108310244).

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

81743440 is a wasteful number, since it uses less digits than its factorization.

81743440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1021806 (or 1021800 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 31.

The square root of 81743440 is about 9041.2078839058. The cubic root of 81743440 is about 433.9945775760.

The spelling of 81743440 in words is "eighty-one million, seven hundred forty-three thousand, four hundred forty".