81961303660 has 24 divisors (see below), whose sum is σ = 172129638240. Its totient is φ = 32782445184.

The previous prime is 81961303657. The next prime is 81961303663. The reversal of 81961303660 is 6630316918.

It is an interprime number because it is at equal distance from previous prime (81961303657) and next prime (81961303663).

It is not an unprimeable number, because it can be changed into a prime (81961303663) 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, 216457 + ... + 459103.

It is an arithmetic number, because the mean of its divisors is an integer number (7172068260).

Almost surely, 2^81961303660 is an apocalyptic number.

It is an amenable number.

81961303660 is an abundant number, since it is smaller than the sum of its proper divisors (90168334580).

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

81961303660 is a wasteful number, since it uses less digits than its factorization.

81961303660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259545 (or 259543 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 43.

The spelling of 81961303660 in words is "eighty-one billion, nine hundred sixty-one million, three hundred three thousand, six hundred sixty".