81647375040 has 1008 divisors, whose sum is σ = 359789882400. Its totient is φ = 16804085760.

The previous prime is 81647375003. The next prime is 81647375057. The reversal of 81647375040 is 4057374618.

81647375040 is a `hidden beast` number, since 81 + 64 + 7 + 3 + 7 + 504 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1008).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 231295504 + ... + 231295856.

Almost surely, 2^81647375040 is an apocalyptic number.

81647375040 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 81647375040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179894941200).

81647375040 is an abundant number, since it is smaller than the sum of its proper divisors (278142507360).

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

81647375040 is a wasteful number, since it uses less digits than its factorization.

81647375040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550 (or 530 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 45.

The spelling of 81647375040 in words is "eighty-one billion, six hundred forty-seven million, three hundred seventy-five thousand, forty".