81159415213968 has 640 divisors, whose sum is σ = 294583635440640. Its totient is φ = 20820509982720.

The previous prime is 81159415213967. The next prime is 81159415213969. The reversal of 81159415213968 is 86931251495118.

It is a happy number.

81159415213968 is a `hidden beast` number, since 8 + 1 + 1 + 5 + 9 + 41 + 521 + 3 + 9 + 68 = 666.

It is an interprime number because it is at equal distance from previous prime (81159415213967) and next prime (81159415213969).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (81159415213967) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 543099196 + ... + 543248612.

It is an arithmetic number, because the mean of its divisors is an integer number (460286930376).

Almost surely, 2^{81159415213968} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81159415213968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147291817720320).

81159415213968 is an abundant number, since it is smaller than the sum of its proper divisors (213424220226672).

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

81159415213968 is a wasteful number, since it uses less digits than its factorization.

81159415213968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149832 (or 149820 counting only the distinct ones).

The product of its digits is 18662400, while the sum is 63.

The spelling of 81159415213968 in words is "eighty-one trillion, one hundred fifty-nine billion, four hundred fifteen million, two hundred thirteen thousand, nine hundred sixty-eight".