81971463490560 has 2112 divisors, whose sum is σ = 346624718469120. Its totient is φ = 17994733977600.

The previous prime is 81971463490517. The next prime is 81971463490577. The reversal of 81971463490560 is 6509436417918.

81971463490560 is a `hidden beast` number, since 8 + 1 + 9 + 7 + 1 + 4 + 63 + 4 + 9 + 0 + 560 = 666.

It is a super-2 number, since 2×81971463490560² (a number of 29 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 168319226637 + ... + 168319227123.

Almost surely, 2^{81971463490560} is an apocalyptic number.

81971463490560 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 81971463490560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (173312359234560).

81971463490560 is an abundant number, since it is smaller than the sum of its proper divisors (264653254978560).

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

81971463490560 is a wasteful number, since it uses less digits than its factorization.

81971463490560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 771 (or 716 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 63.

The spelling of 81971463490560 in words is "eighty-one trillion, nine hundred seventy-one billion, four hundred sixty-three million, four hundred ninety thousand, five hundred sixty".