81291406684 has 24 divisors (see below), whose sum is σ = 151727688000. Its totient is φ = 37975543296.

The previous prime is 81291406681. The next prime is 81291406687. The reversal of 81291406684 is 48660419218.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81291406681) and next prime (81291406687).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81291406681) 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, 4353684 + ... + 4372315.

It is an arithmetic number, because the mean of its divisors is an integer number (6321987000).

Almost surely, 2^81291406684 is an apocalyptic number.

It is an amenable number.

81291406684 is a deficient number, since it is larger than the sum of its proper divisors (70436281316).

81291406684 is a wasteful number, since it uses less digits than its factorization.

81291406684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8726157 (or 8726155 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 49.

The spelling of 81291406684 in words is "eighty-one billion, two hundred ninety-one million, four hundred six thousand, six hundred eighty-four".