81206461440 has 704 divisors, whose sum is σ = 315558969600. Its totient is φ = 19683606528.

The previous prime is 81206461429. The next prime is 81206461459. The reversal of 81206461440 is 4416460218.

It is a happy number.

81206461440 is a `hidden beast` number, since 8 + 1 + 2 + 0 + 646 + 1 + 4 + 4 + 0 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 81206461395 and 81206461404.

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, 131189451 + ... + 131190069.

Almost surely, 2^81206461440 is an apocalyptic number.

81206461440 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 81206461440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157779484800).

81206461440 is an abundant number, since it is smaller than the sum of its proper divisors (234352508160).

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

81206461440 is a wasteful number, since it uses less digits than its factorization.

81206461440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 739 (or 715 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The spelling of 81206461440 in words is "eighty-one billion, two hundred six million, four hundred sixty-one thousand, four hundred forty".