81642700 has 18 divisors (see below), whose sum is σ = 177164876. Its totient is φ = 32657040.

The previous prime is 81642697. The next prime is 81642707. The reversal of 81642700 is 724618.

It is not an unprimeable number, because it can be changed into a prime (81642707) 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, 408114 + ... + 408313.

Almost surely, 2^81642700 is an apocalyptic number.

It is an amenable number.

81642700 is an abundant number, since it is smaller than the sum of its proper divisors (95522176).

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

81642700 is a wasteful number, since it uses less digits than its factorization.

81642700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816441 (or 816434 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 81642700 is about 9035.6350081220. The cubic root of 81642700 is about 433.8162204040.

The spelling of 81642700 in words is "eighty-one million, six hundred forty-two thousand, seven hundred".