81781354036 has 6 divisors (see below), whose sum is σ = 143117369570. Its totient is φ = 40890677016.

The previous prime is 81781354013. The next prime is 81781354049. The reversal of 81781354036 is 63045318718.

It can be written as a sum of positive squares in only one way, i.e., 74038410000 + 7742944036 = 272100^2 + 87994^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10222669251 + ... + 10222669258.

Almost surely, 2^81781354036 is an apocalyptic number.

It is an amenable number.

81781354036 is a deficient number, since it is larger than the sum of its proper divisors (61336015534).

81781354036 is a wasteful number, since it uses less digits than its factorization.

81781354036 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20445338513 (or 20445338511 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 46.

The spelling of 81781354036 in words is "eighty-one billion, seven hundred eighty-one million, three hundred fifty-four thousand, thirty-six".