81390124989 has 12 divisors (see below), whose sum is σ = 120064865856. Its totient is φ = 53105613192.

The previous prime is 81390124973. The next prime is 81390125017. The reversal of 81390124989 is 98942109318.

81390124989 is a `hidden beast` number, since 8 + 1 + 390 + 1 + 249 + 8 + 9 = 666.

It is not a de Polignac number, because 81390124989 - 2⁴ = 81390124973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390124939) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 96205399 + ... + 96206244.

It is an arithmetic number, because the mean of its divisors is an integer number (10005405488).

Almost surely, 2^81390124989 is an apocalyptic number.

It is an amenable number.

81390124989 is a deficient number, since it is larger than the sum of its proper divisors (38674740867).

81390124989 is a wasteful number, since it uses less digits than its factorization.

81390124989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192411696 (or 192411693 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 54.

The spelling of 81390124989 in words is "eighty-one billion, three hundred ninety million, one hundred twenty-four thousand, nine hundred eighty-nine".