81666738 has 32 divisors (see below), whose sum is σ = 184564800. Its totient is φ = 26759808.

The previous prime is 81666719. The next prime is 81666757. The reversal of 81666738 is 83766618.

It is an interprime number because it is at equal distance from previous prime (81666719) and next prime (81666757).

It is a junction number, because it is equal to n+sod(n) for n = 81666693 and 81666702.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 9631 + ... + 16002.

It is an arithmetic number, because the mean of its divisors is an integer number (5767650).

Almost surely, 2^81666738 is an apocalyptic number.

81666738 is an abundant number, since it is smaller than the sum of its proper divisors (102898062).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81666738 is a wasteful number, since it uses less digits than its factorization.

81666738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25703 (or 25697 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The square root of 81666738 is about 9036.9650879042. The cubic root of 81666738 is about 433.8587922895.

The spelling of 81666738 in words is "eighty-one million, six hundred sixty-six thousand, seven hundred thirty-eight".