81219801600 has 1800 divisors, whose sum is σ = 374272259328. Its totient is φ = 17020108800.

The previous prime is 81219801599. The next prime is 81219801653. The reversal of 81219801600 is 610891218.

It is a tau number, because it is divible by the number of its divisors (1800).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 179 ways as a sum of consecutive naturals, for example, 2619993585 + ... + 2619993615.

Almost surely, 2^81219801600 is an apocalyptic number.

81219801600 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 81219801600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (187136129664).

81219801600 is an abundant number, since it is smaller than the sum of its proper divisors (293052457728).

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

81219801600 is a wasteful number, since it uses less digits than its factorization.

81219801600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116 (or 67 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 36.

The spelling of 81219801600 in words is "eighty-one billion, two hundred nineteen million, eight hundred one thousand, six hundred".