81549966 has 16 divisors (see below), whose sum is σ = 164181888. Its totient is φ = 27003000.

The previous prime is 81549947. The next prime is 81549967. The reversal of 81549966 is 66994518.

81549966 is a modest number, since divided by 9966 gives 8154 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81549967) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44100 + ... + 45911.

It is an arithmetic number, because the mean of its divisors is an integer number (10261368).

Almost surely, 2^81549966 is an apocalyptic number.

81549966 is an abundant number, since it is smaller than the sum of its proper divisors (82631922).

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

81549966 is a wasteful number, since it uses less digits than its factorization.

81549966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90167.

The product of its digits is 466560, while the sum is 48.

The square root of 81549966 is about 9030.5019794029. The cubic root of 81549966 is about 433.6519078788.

The spelling of 81549966 in words is "eighty-one million, five hundred forty-nine thousand, nine hundred sixty-six".