81775780 has 24 divisors (see below), whose sum is σ = 181831608. Its totient is φ = 30786048.

The previous prime is 81775751. The next prime is 81775783. The reversal of 81775780 is 8757718.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 10407076 + 71368704 = 3226^2 + 8448^2 .

It is not an unprimeable number, because it can be changed into a prime (81775783) 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, 119919 + ... + 120598.

It is an arithmetic number, because the mean of its divisors is an integer number (7576317).

Almost surely, 2^81775780 is an apocalyptic number.

It is an amenable number.

81775780 is an abundant number, since it is smaller than the sum of its proper divisors (100055828).

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

81775780 is a wasteful number, since it uses less digits than its factorization.

81775780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240543 (or 240541 counting only the distinct ones).

The product of its (nonzero) digits is 109760, while the sum is 43.

The square root of 81775780 is about 9042.9961848936. The cubic root of 81775780 is about 434.0518035100.

The spelling of 81775780 in words is "eighty-one million, seven hundred seventy-five thousand, seven hundred eighty".