81821416978 has 32 divisors (see below), whose sum is σ = 140565680640. Its totient is φ = 34991308800.

The previous prime is 81821416969. The next prime is 81821416979. The reversal of 81821416978 is 87961412818.

It is not an unprimeable number, because it can be changed into a prime (81821416979) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17040178 + ... + 17044978.

It is an arithmetic number, because the mean of its divisors is an integer number (4392677520).

Almost surely, 2^81821416978 is an apocalyptic number.

81821416978 is a deficient number, since it is larger than the sum of its proper divisors (58744263662).

81821416978 is a wasteful number, since it uses less digits than its factorization.

81821416978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7162.

The product of its digits is 1548288, while the sum is 55.

The spelling of 81821416978 in words is "eighty-one billion, eight hundred twenty-one million, four hundred sixteen thousand, nine hundred seventy-eight".