81941664 has 48 divisors (see below), whose sum is σ = 245827008. Its totient is φ = 23411712.

The previous prime is 81941659. The next prime is 81941669. The reversal of 81941664 is 46614918.

It is an interprime number because it is at equal distance from previous prime (81941659) and next prime (81941669).

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (81941669) 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, 60297 + ... + 61640.

It is an arithmetic number, because the mean of its divisors is an integer number (5121396).

Almost surely, 2^81941664 is an apocalyptic number.

81941664 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81941664 is an abundant number, since it is smaller than the sum of its proper divisors (163885344).

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

81941664 is a wasteful number, since it uses less digits than its factorization.

81941664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121957 (or 121949 counting only the distinct ones).

The product of its digits is 41472, while the sum is 39.

The square root of 81941664 is about 9052.1634983025. The cubic root of 81941664 is about 434.3450998793.

The spelling of 81941664 in words is "eighty-one million, nine hundred forty-one thousand, six hundred sixty-four".