81425917440 has 1120 divisors, whose sum is σ = 350362146816. Its totient is φ = 17736744960.

The previous prime is 81425917429. The next prime is 81425917451. The reversal of 81425917440 is 4471952418.

81425917440 is a `hidden beast` number, since 8 + 14 + 2 + 591 + 7 + 4 + 40 = 666.

It is an interprime number because it is at equal distance from previous prime (81425917429) and next prime (81425917451).

It is a tau number, because it is divible by the number of its divisors (1120).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 300464505 + ... + 300464775.

Almost surely, 2^81425917440 is an apocalyptic number.

81425917440 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 81425917440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (175181073408).

81425917440 is an abundant number, since it is smaller than the sum of its proper divisors (268936229376).

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

81425917440 is an equidigital number, since it uses as much as digits as its factorization.

81425917440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342 (or 311 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The spelling of 81425917440 in words is "eighty-one billion, four hundred twenty-five million, nine hundred seventeen thousand, four hundred forty".