81402347520 has 960 divisors, whose sum is σ = 330291360000. Its totient is φ = 18855493632.

The previous prime is 81402347519. The next prime is 81402347561. The reversal of 81402347520 is 2574320418.

It is a happy number.

81402347520 is a `hidden beast` number, since 8 + 140 + 23 + 475 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 546324406 + ... + 546324554.

It is an arithmetic number, because the mean of its divisors is an integer number (344053500).

Almost surely, 2^81402347520 is an apocalyptic number.

81402347520 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 81402347520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (165145680000).

81402347520 is an abundant number, since it is smaller than the sum of its proper divisors (248889012480).

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

81402347520 is a wasteful number, since it uses less digits than its factorization.

81402347520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223 (or 191 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 36.

Adding to 81402347520 its reverse (2574320418), we get a palindrome (83976667938).

The spelling of 81402347520 in words is "eighty-one billion, four hundred two million, three hundred forty-seven thousand, five hundred twenty".