81421516 has 12 divisors (see below), whose sum is σ = 155441160. Its totient is φ = 37009760.

The previous prime is 81421513. The next prime is 81421547. The reversal of 81421516 is 61512418.

It is not an unprimeable number, because it can be changed into a prime (81421511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 925201 + ... + 925288.

It is an arithmetic number, because the mean of its divisors is an integer number (12953430).

Almost surely, 2^81421516 is an apocalyptic number.

It is an amenable number.

81421516 is a deficient number, since it is larger than the sum of its proper divisors (74019644).

81421516 is a wasteful number, since it uses less digits than its factorization.

81421516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1850504 (or 1850502 counting only the distinct ones).

The product of its digits is 1920, while the sum is 28.

The square root of 81421516 is about 9023.3871689073. The cubic root of 81421516 is about 433.4241053761.

The spelling of 81421516 in words is "eighty-one million, four hundred twenty-one thousand, five hundred sixteen".