81399100 has 18 divisors (see below), whose sum is σ = 176636264. Its totient is φ = 32559600.

The previous prime is 81399083. The next prime is 81399107. The reversal of 81399100 is 199318.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81399107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 406896 + ... + 407095.

Almost surely, 2^81399100 is an apocalyptic number.

It is an amenable number.

81399100 is an abundant number, since it is smaller than the sum of its proper divisors (95237164).

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

81399100 is a wasteful number, since it uses less digits than its factorization.

81399100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814005 (or 813998 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 81399100 is about 9022.1449777755. The cubic root of 81399100 is about 433.3843266749.

The spelling of 81399100 in words is "eighty-one million, three hundred ninety-nine thousand, one hundred".