81961966 has 8 divisors (see below), whose sum is σ = 122986080. Its totient is φ = 40966608.

The previous prime is 81961961. The next prime is 81961967. The reversal of 81961966 is 66916918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81961961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2610 + ... + 13066.

It is an arithmetic number, because the mean of its divisors is an integer number (15373260).

Almost surely, 2^81961966 is an apocalyptic number.

81961966 is a deficient number, since it is larger than the sum of its proper divisors (41024114).

81961966 is a wasteful number, since it uses less digits than its factorization.

81961966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14378.

The product of its digits is 139968, while the sum is 46.

The square root of 81961966 is about 9053.2848182303. The cubic root of 81961966 is about 434.3809682668.

The spelling of 81961966 in words is "eighty-one million, nine hundred sixty-one thousand, nine hundred sixty-six".