81779322240 has 1536 divisors, whose sum is σ = 371195136000. Its totient is φ = 16437657600.

The previous prime is 81779322227. The next prime is 81779322259. The reversal of 81779322240 is 4222397718.

81779322240 is a `hidden beast` number, since 8 + 17 + 79 + 322 + 240 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1151821405 + ... + 1151821475.

It is an arithmetic number, because the mean of its divisors is an integer number (241663500).

Almost surely, 2^81779322240 is an apocalyptic number.

81779322240 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 81779322240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (185597568000).

81779322240 is an abundant number, since it is smaller than the sum of its proper divisors (289415813760).

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

81779322240 is a wasteful number, since it uses less digits than its factorization.

81779322240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 45.

The spelling of 81779322240 in words is "eighty-one billion, seven hundred seventy-nine million, three hundred twenty-two thousand, two hundred forty".