81733440778 has 16 divisors (see below), whose sum is σ = 133753840704. Its totient is φ = 37149283360.

The previous prime is 81733440773. The next prime is 81733440791. The reversal of 81733440778 is 87704433718.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81733440773) 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, 283251 + ... + 493657.

It is an arithmetic number, because the mean of its divisors is an integer number (8359615044).

Almost surely, 2^81733440778 is an apocalyptic number.

81733440778 is a deficient number, since it is larger than the sum of its proper divisors (52020399926).

81733440778 is a wasteful number, since it uses less digits than its factorization.

81733440778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228077.

The product of its (nonzero) digits is 3161088, while the sum is 52.

The spelling of 81733440778 in words is "eighty-one billion, seven hundred thirty-three million, four hundred forty thousand, seven hundred seventy-eight".