81308987887 has 8 divisors (see below), whose sum is σ = 86826061440. Its totient is φ = 75972802080.

The previous prime is 81308987869. The next prime is 81308987909. The reversal of 81308987887 is 78878980318.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81308987887 is a prime.

It is a super-2 number, since 2×81308987887² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81308987827) 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, 45221008 + ... + 45222805.

It is an arithmetic number, because the mean of its divisors is an integer number (10853257680).

Almost surely, 2^81308987887 is an apocalyptic number.

81308987887 is a deficient number, since it is larger than the sum of its proper divisors (5517073553).

81308987887 is a wasteful number, since it uses less digits than its factorization.

81308987887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90443873.

The product of its (nonzero) digits is 43352064, while the sum is 67.

The spelling of 81308987887 in words is "eighty-one billion, three hundred eight million, nine hundred eighty-seven thousand, eight hundred eighty-seven".