81531610776 has 672 divisors, whose sum is σ = 299149465680. Its totient is φ = 20575296000.

The previous prime is 81531610759. The next prime is 81531610777. The reversal of 81531610776 is 67701613518.

81531610776 is a `hidden beast` number, since 8 + 1 + 531 + 6 + 107 + 7 + 6 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81531610777) by changing a digit.

It is a polite number, since it can be written in 167 ways as a sum of consecutive naturals, for example, 116307226 + ... + 116307926.

Almost surely, 2^81531610776 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 81531610776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149574732840).

81531610776 is an abundant number, since it is smaller than the sum of its proper divisors (217617854904).

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

81531610776 is a wasteful number, since it uses less digits than its factorization.

81531610776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 787 (or 761 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The spelling of 81531610776 in words is "eighty-one billion, five hundred thirty-one million, six hundred ten thousand, seven hundred seventy-six".