81886913 has 2 divisors, whose sum is σ = 81886914. Its totient is φ = 81886912.

The previous prime is 81886879. The next prime is 81886939. The reversal of 81886913 is 31968818.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72046144 + 9840769 = 8488^2 + 3137^2 .

It is a cyclic number.

It is not a de Polignac number, because 81886913 - 2²² = 77692609 is a prime.

It is not a weakly prime, because it can be changed into another prime (81886213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40943456 + 40943457.

It is an arithmetic number, because the mean of its divisors is an integer number (40943457).

Almost surely, 2^81886913 is an apocalyptic number.

It is an amenable number.

81886913 is a deficient number, since it is larger than the sum of its proper divisors (1).

81886913 is an equidigital number, since it uses as much as digits as its factorization.

81886913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82944, while the sum is 44.

The square root of 81886913 is about 9049.1387988029. The cubic root of 81886913 is about 434.2483394691.

The spelling of 81886913 in words is "eighty-one million, eight hundred eighty-six thousand, nine hundred thirteen".