81778244 has 12 divisors (see below), whose sum is σ = 143390268. Its totient is φ = 40809600.

The previous prime is 81778219. The next prime is 81778253. The reversal of 81778244 is 44287718.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21529600 + 60248644 = 4640^2 + 7762^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17537 + ... + 21704.

It is an arithmetic number, because the mean of its divisors is an integer number (11949189).

Almost surely, 2^81778244 is an apocalyptic number.

It is an amenable number.

81778244 is a deficient number, since it is larger than the sum of its proper divisors (61612024).

81778244 is a wasteful number, since it uses less digits than its factorization.

81778244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39766 (or 39764 counting only the distinct ones).

The product of its digits is 100352, while the sum is 41.

The square root of 81778244 is about 9043.1324218990. The cubic root of 81778244 is about 434.0561629626.

The spelling of 81778244 in words is "eighty-one million, seven hundred seventy-eight thousand, two hundred forty-four".