81801700 has 18 divisors (see below), whose sum is σ = 177509906. Its totient is φ = 32720640.

The previous prime is 81801697. The next prime is 81801703. The reversal of 81801700 is 710818.

It is an interprime number because it is at equal distance from previous prime (81801697) and next prime (81801703).

It can be written as a sum of positive squares in 3 ways, for example, as 224676 + 81577024 = 474^2 + 9032^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (81801703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 408909 + ... + 409108.

Almost surely, 2^81801700 is an apocalyptic number.

It is an amenable number.

81801700 is an abundant number, since it is smaller than the sum of its proper divisors (95708206).

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

81801700 is a wasteful number, since it uses less digits than its factorization.

81801700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 818031 (or 818024 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 25.

The square root of 81801700 is about 9044.4292246664. The cubic root of 81801700 is about 434.0976583026.

The spelling of 81801700 in words is "eighty-one million, eight hundred one thousand, seven hundred".