81667040832 has 630 divisors, whose sum is σ = 273662635554. Its totient is φ = 24067031040.

The previous prime is 81667040827. The next prime is 81667040837. The reversal of 81667040832 is 23804076618.

It is an interprime number because it is at equal distance from previous prime (81667040827) and next prime (81667040837).

It can be written as a sum of positive squares in 3 ways, for example, as 44836416 + 81622204416 = 6696^2 + 285696^2 .

It is not an unprimeable number, because it can be changed into a prime (81667040837) by changing a digit.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 841928208 + ... + 841928304.

Almost surely, 2^81667040832 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 81667040832, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136831317777).

81667040832 is an abundant number, since it is smaller than the sum of its proper divisors (191995594722).

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

81667040832 is a wasteful number, since it uses less digits than its factorization.

81667040832 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209 (or 146 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 81667040832 in words is "eighty-one billion, six hundred sixty-seven million, forty thousand, eight hundred thirty-two".