81700187 has 4 divisors (see below), whose sum is σ = 82449840. Its totient is φ = 80950536.

The previous prime is 81700153. The next prime is 81700207. The reversal of 81700187 is 78100718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81700187 - 2¹⁸ = 81438043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81703187) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 374663 + ... + 374880.

It is an arithmetic number, because the mean of its divisors is an integer number (20612460).

Almost surely, 2^81700187 is an apocalyptic number.

81700187 is a deficient number, since it is larger than the sum of its proper divisors (749653).

81700187 is a wasteful number, since it uses less digits than its factorization.

81700187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 749652.

The product of its (nonzero) digits is 3136, while the sum is 32.

The square root of 81700187 is about 9038.8155750629. The cubic root of 81700187 is about 433.9180173884.

The spelling of 81700187 in words is "eighty-one million, seven hundred thousand, one hundred eighty-seven".