81778449600 has 504 divisors, whose sum is σ = 296610682368. Its totient is φ = 21366374400.

The previous prime is 81778449481. The next prime is 81778449637. The reversal of 81778449600 is 694487718.

It is a happy number.

81778449600 is a `hidden beast` number, since 8 + 1 + 77 + 84 + 496 + 0 + 0 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 177393370 + ... + 177393830.

Almost surely, 2^81778449600 is an apocalyptic number.

81778449600 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 81778449600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148305341184).

81778449600 is an abundant number, since it is smaller than the sum of its proper divisors (214832232768).

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

81778449600 is a wasteful number, since it uses less digits than its factorization.

81778449600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 713 (or 695 counting only the distinct ones).

The product of its (nonzero) digits is 2709504, while the sum is 54.

The spelling of 81778449600 in words is "eighty-one billion, seven hundred seventy-eight million, four hundred forty-nine thousand, six hundred".