81212813684 has 24 divisors (see below), whose sum is σ = 142575793920. Its totient is φ = 40476955904.

The previous prime is 81212813599. The next prime is 81212813701. The reversal of 81212813684 is 48631821218.

It is a super-2 number, since 2×81212813684² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4734347 + ... + 4751469.

It is an arithmetic number, because the mean of its divisors is an integer number (5940658080).

Almost surely, 2^81212813684 is an apocalyptic number.

It is an amenable number.

81212813684 is a deficient number, since it is larger than the sum of its proper divisors (61362980236).

81212813684 is a wasteful number, since it uses less digits than its factorization.

81212813684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20839 (or 20837 counting only the distinct ones).

The product of its digits is 147456, while the sum is 44.

The spelling of 81212813684 in words is "eighty-one billion, two hundred twelve million, eight hundred thirteen thousand, six hundred eighty-four".