81961303661 has 8 divisors (see below), whose sum is σ = 82114819584. Its totient is φ = 81807863760.

The previous prime is 81961303657. The next prime is 81961303663. The reversal of 81961303661 is 16630316918.

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

It is a cyclic number.

It is not a de Polignac number, because 81961303661 - 2² = 81961303657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81961303663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2429636 + ... + 2463138.

It is an arithmetic number, because the mean of its divisors is an integer number (10264352448).

Almost surely, 2^81961303661 is an apocalyptic number.

It is an amenable number.

81961303661 is a deficient number, since it is larger than the sum of its proper divisors (153515923).

81961303661 is a wasteful number, since it uses less digits than its factorization.

81961303661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38011.

The product of its (nonzero) digits is 139968, while the sum is 44.

The spelling of 81961303661 in words is "eighty-one billion, nine hundred sixty-one million, three hundred three thousand, six hundred sixty-one".