81886213 has 2 divisors, whose sum is σ = 81886214. Its totient is φ = 81886212.

The previous prime is 81886201. The next prime is 81886237. The reversal of 81886213 is 31268818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67125249 + 14760964 = 8193^2 + 3842^2 .

It is a cyclic number.

It is not a de Polignac number, because 81886213 - 2¹³ = 81878021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81886253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40943106 + 40943107.

It is an arithmetic number, because the mean of its divisors is an integer number (40943107).

Almost surely, 2^81886213 is an apocalyptic number.

It is an amenable number.

81886213 is a deficient number, since it is larger than the sum of its proper divisors (1).

81886213 is an equidigital number, since it uses as much as digits as its factorization.

81886213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18432, while the sum is 37.

The square root of 81886213 is about 9049.1001210065. The cubic root of 81886213 is about 434.2471020930.

The spelling of 81886213 in words is "eighty-one million, eight hundred eighty-six thousand, two hundred thirteen".