81201004400 has 30 divisors (see below), whose sum is σ = 195085414032. Its totient is φ = 32480401600.

The previous prime is 81201004397. The next prime is 81201004403. The reversal of 81201004400 is 440010218.

It is an interprime number because it is at equal distance from previous prime (81201004397) and next prime (81201004403).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81201004403) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 101500856 + ... + 101501655.

Almost surely, 2^81201004400 is an apocalyptic number.

81201004400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81201004400 is an abundant number, since it is smaller than the sum of its proper divisors (113884409632).

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

81201004400 is a wasteful number, since it uses less digits than its factorization.

81201004400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203002529 (or 203002518 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 81201004400 its reverse (440010218), we get a palindrome (81641014618).

The spelling of 81201004400 in words is "eighty-one billion, two hundred one million, four thousand, four hundred".