81799151616 has 608 divisors, whose sum is σ = 300647137280. Its totient is φ = 21403533312.

The previous prime is 81799151611. The next prime is 81799151627. The reversal of 81799151616 is 61615199718.

It is a happy number.

81799151616 is a `hidden beast` number, since 8 + 1 + 7 + 9 + 9 + 15 + 1 + 616 = 666.

It is a super-2 number, since 2×81799151616² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81799151611) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 644087745 + ... + 644087871.

Almost surely, 2^81799151616 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 81799151616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150323568640).

81799151616 is an abundant number, since it is smaller than the sum of its proper divisors (218847985664).

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

81799151616 is an equidigital number, since it uses as much as digits as its factorization.

81799151616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192 (or 152 counting only the distinct ones).

The product of its digits is 816480, while the sum is 54.

The spelling of 81799151616 in words is "eighty-one billion, seven hundred ninety-nine million, one hundred fifty-one thousand, six hundred sixteen".