81768788 has 12 divisors (see below), whose sum is σ = 143232180. Its totient is φ = 40845312.

The previous prime is 81768781. The next prime is 81768803. The reversal of 81768788 is 88786718.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17960644 + 63808144 = 4238^2 + 7988^2 .

It is a super-2 number, since 2×81768788² = 13372269381977888, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81768781) 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, 4781 + ... + 13652.

It is an arithmetic number, because the mean of its divisors is an integer number (11936015).

Almost surely, 2^81768788 is an apocalyptic number.

It is an amenable number.

81768788 is a deficient number, since it is larger than the sum of its proper divisors (61463392).

81768788 is a wasteful number, since it uses less digits than its factorization.

81768788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19546 (or 19544 counting only the distinct ones).

The product of its digits is 1204224, while the sum is 53.

The square root of 81768788 is about 9042.6095790983. The cubic root of 81768788 is about 434.0394323788.

The spelling of 81768788 in words is "eighty-one million, seven hundred sixty-eight thousand, seven hundred eighty-eight".