81964660 has 12 divisors (see below), whose sum is σ = 172125828. Its totient is φ = 32785856.

The previous prime is 81964607. The next prime is 81964669. The reversal of 81964660 is 6646918.

It can be written as a sum of positive squares in 2 ways, for example, as 53640976 + 28323684 = 7324^2 + 5322^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81964669) 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, 2049097 + ... + 2049136.

It is an arithmetic number, because the mean of its divisors is an integer number (14343819).

Almost surely, 2^81964660 is an apocalyptic number.

It is an amenable number.

81964660 is an abundant number, since it is smaller than the sum of its proper divisors (90161168).

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

81964660 is a wasteful number, since it uses less digits than its factorization.

81964660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4098242 (or 4098240 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 40.

The square root of 81964660 is about 9053.4336027830. The cubic root of 81964660 is about 434.3857274234.

The spelling of 81964660 in words is "eighty-one million, nine hundred sixty-four thousand, six hundred sixty".