81700211 has 4 divisors (see below), whose sum is σ = 82241424. Its totient is φ = 81159000.

The previous prime is 81700207. The next prime is 81700231. The reversal of 81700211 is 11200718.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11200718 = 2 ⋅5600359.

It is a cyclic number.

It is not a de Polignac number, because 81700211 - 2² = 81700207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81700231) 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, 270380 + ... + 270681.

It is an arithmetic number, because the mean of its divisors is an integer number (20560356).

Almost surely, 2^81700211 is an apocalyptic number.

81700211 is a deficient number, since it is larger than the sum of its proper divisors (541213).

81700211 is a wasteful number, since it uses less digits than its factorization.

81700211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541212.

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 81700211 is about 9038.8169026704. The cubic root of 81700211 is about 433.9180598772.

Adding to 81700211 its reverse (11200718), we get a palindrome (92900929).

The spelling of 81700211 in words is "eighty-one million, seven hundred thousand, two hundred eleven".