81129700 has 18 divisors (see below), whose sum is σ = 176051666. Its totient is φ = 32451840.

The previous prime is 81129679. The next prime is 81129703. The reversal of 81129700 is 792118.

It can be written as a sum of positive squares in 3 ways, for example, as 2842596 + 78287104 = 1686^2 + 8848^2 .

It is not an unprimeable number, because it can be changed into a prime (81129703) 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, 405549 + ... + 405748.

Almost surely, 2^81129700 is an apocalyptic number.

It is an amenable number.

81129700 is an abundant number, since it is smaller than the sum of its proper divisors (94921966).

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

81129700 is a wasteful number, since it uses less digits than its factorization.

81129700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 811311 (or 811304 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 81129700 is about 9007.2026734164. The cubic root of 81129700 is about 432.9056859265.

The spelling of 81129700 in words is "eighty-one million, one hundred twenty-nine thousand, seven hundred".