81705550 has 24 divisors (see below), whose sum is σ = 152222400. Its totient is φ = 32628480.

The previous prime is 81705539. The next prime is 81705551. The reversal of 81705550 is 5550718.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81705551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45571 + ... + 47329.

It is an arithmetic number, because the mean of its divisors is an integer number (6342600).

Almost surely, 2^81705550 is an apocalyptic number.

81705550 is a deficient number, since it is larger than the sum of its proper divisors (70516850).

81705550 is a wasteful number, since it uses less digits than its factorization.

81705550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2700 (or 2695 counting only the distinct ones).

The product of its (nonzero) digits is 7000, while the sum is 31.

The square root of 81705550 is about 9039.1122351700. The cubic root of 81705550 is about 433.9275116604.

The spelling of 81705550 in words is "eighty-one million, seven hundred five thousand, five hundred fifty".