81764281276840 has 32 divisors (see below), whose sum is σ = 194791375984680. Its totient is φ = 30781847068672.

The previous prime is 81764281276829. The next prime is 81764281276897. The reversal of 81764281276840 is 4867218246718.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 50981913386244 + 30782367890596 = 7140162^2 + 5548186^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60120794377 + ... + 60120795736.

Almost surely, 2^{81764281276840} is an apocalyptic number.

It is an amenable number.

81764281276840 is an abundant number, since it is smaller than the sum of its proper divisors (113027094707840).

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

81764281276840 is a wasteful number, since it uses less digits than its factorization.

81764281276840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120241590141 (or 120241590137 counting only the distinct ones).

The product of its (nonzero) digits is 57802752, while the sum is 64.

The spelling of 81764281276840 in words is "eighty-one trillion, seven hundred sixty-four billion, two hundred eighty-one million, two hundred seventy-six thousand, eight hundred forty".