81691459200 has 768 divisors, whose sum is σ = 324360489600. Its totient is φ = 19959644160.

The previous prime is 81691459181. The next prime is 81691459217. The reversal of 81691459200 is 295419618.

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

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 288662259 + ... + 288662541.

Almost surely, 2^81691459200 is an apocalyptic number.

81691459200 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 81691459200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162180244800).

81691459200 is an abundant number, since it is smaller than the sum of its proper divisors (242669030400).

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

81691459200 is a wasteful number, since it uses less digits than its factorization.

81691459200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 586 (or 563 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The spelling of 81691459200 in words is "eighty-one billion, six hundred ninety-one million, four hundred fifty-nine thousand, two hundred".