81292121600 has 120 divisors (see below), whose sum is σ = 202257902880. Its totient is φ = 32379576320.

The previous prime is 81292121507. The next prime is 81292121609. The reversal of 81292121600 is 612129218.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81292121609) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3045914 + ... + 3072486.

It is an arithmetic number, because the mean of its divisors is an integer number (1685482524).

Almost surely, 2^81292121600 is an apocalyptic number.

81292121600 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 81292121600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101128951440).

81292121600 is an abundant number, since it is smaller than the sum of its proper divisors (120965781280).

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

81292121600 is a wasteful number, since it uses less digits than its factorization.

81292121600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26840 (or 26819 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 32.

The spelling of 81292121600 in words is "eighty-one billion, two hundred ninety-two million, one hundred twenty-one thousand, six hundred".