81669082328640 has 336 divisors, whose sum is σ = 281889997944048. Its totient is φ = 21702384156672.

The previous prime is 81669082328567. The next prime is 81669082328657. The reversal of 81669082328640 is 4682328096618.

81669082328640 is a `hidden beast` number, since 8 + 166 + 90 + 8 + 2 + 328 + 64 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 4753516225536 + 76915566103104 = 2180256^2 + 8770152^2 .

It is a hoax number, since the sum of its digits (63) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1017351544 + ... + 1017431816.

Almost surely, 2^{81669082328640} is an apocalyptic number.

81669082328640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81669082328640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140944998972024).

81669082328640 is an abundant number, since it is smaller than the sum of its proper divisors (200220915615408).

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

81669082328640 is a wasteful number, since it uses less digits than its factorization.

81669082328640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81526 (or 81513 counting only the distinct ones).

The product of its (nonzero) digits is 47775744, while the sum is 63.

The spelling of 81669082328640 in words is "eighty-one trillion, six hundred sixty-nine billion, eighty-two million, three hundred twenty-eight thousand, six hundred forty".