81515210040 has 192 divisors, whose sum is σ = 291089635200. Its totient is φ = 19618963200.

The previous prime is 81515210039. The next prime is 81515210083. The reversal of 81515210040 is 4001251518.

81515210040 is a `hidden beast` number, since 8 + 1 + 515 + 2 + 100 + 40 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 81515209986 and 81515210013.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 476395 + ... + 624485.

It is an arithmetic number, because the mean of its divisors is an integer number (1516091850).

Almost surely, 2^81515210040 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81515210040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145544817600).

81515210040 is an abundant number, since it is smaller than the sum of its proper divisors (209574425160).

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

81515210040 is a wasteful number, since it uses less digits than its factorization.

81515210040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148258 (or 148251 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 27.

Adding to 81515210040 its reverse (4001251518), we get a palindrome (85516461558).

The spelling of 81515210040 in words is "eighty-one billion, five hundred fifteen million, two hundred ten thousand, forty".