81387886840 has 32 divisors (see below), whose sum is σ = 197209111680. Its totient is φ = 30050911872.

The previous prime is 81387886837. The next prime is 81387886843. The reversal of 81387886840 is 4868878318.

It is an interprime number because it is at equal distance from previous prime (81387886837) and next prime (81387886843).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81387886843) 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, 78257064 + ... + 78258103.

It is an arithmetic number, because the mean of its divisors is an integer number (6162784740).

Almost surely, 2^81387886840 is an apocalyptic number.

It is an amenable number.

81387886840 is an abundant number, since it is smaller than the sum of its proper divisors (115821224840).

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

81387886840 is a wasteful number, since it uses less digits than its factorization.

81387886840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156515191 (or 156515187 counting only the distinct ones).

The product of its (nonzero) digits is 16515072, while the sum is 61.

The spelling of 81387886840 in words is "eighty-one billion, three hundred eighty-seven million, eight hundred eighty-six thousand, eight hundred forty".