81640363470 has 128 divisors (see below), whose sum is σ = 206106163200. Its totient is φ = 20671967232.

The previous prime is 81640363421. The next prime is 81640363489. The reversal of 81640363470 is 7436304618.

It is a happy number.

It is a Curzon number.

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, 19770366 + ... + 19774494.

It is an arithmetic number, because the mean of its divisors is an integer number (1610204400).

Almost surely, 2^81640363470 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81640363470, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103053081600).

81640363470 is an abundant number, since it is smaller than the sum of its proper divisors (124465799730).

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

81640363470 is a wasteful number, since it uses less digits than its factorization.

81640363470 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4602.

The product of its (nonzero) digits is 290304, while the sum is 42.

The spelling of 81640363470 in words is "eighty-one billion, six hundred forty million, three hundred sixty-three thousand, four hundred seventy".