81806425784 has 8 divisors (see below), whose sum is σ = 153387048360. Its totient is φ = 40903212888.

The previous prime is 81806425693. The next prime is 81806425807. The reversal of 81806425784 is 48752460818.

It is a tau number, because it is divible by the number of its divisors (8).

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, 5112901604 + ... + 5112901619.

It is an arithmetic number, because the mean of its divisors is an integer number (19173381045).

Almost surely, 2^81806425784 is an apocalyptic number.

It is an amenable number.

81806425784 is a deficient number, since it is larger than the sum of its proper divisors (71580622576).

81806425784 is a wasteful number, since it uses less digits than its factorization.

81806425784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10225803229 (or 10225803225 counting only the distinct ones).

The product of its (nonzero) digits is 3440640, while the sum is 53.

The spelling of 81806425784 in words is "eighty-one billion, eight hundred six million, four hundred twenty-five thousand, seven hundred eighty-four".