81713381 has 2 divisors, whose sum is σ = 81713382. Its totient is φ = 81713380.

The previous prime is 81713377. The next prime is 81713393. The reversal of 81713381 is 18331718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76912900 + 4800481 = 8770^2 + 2191^2 .

It is a cyclic number.

It is not a de Polignac number, because 81713381 - 2² = 81713377 is a prime.

It is a super-2 number, since 2×81713381² = 13354153268902322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81713881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40856690 + 40856691.

It is an arithmetic number, because the mean of its divisors is an integer number (40856691).

Almost surely, 2^81713381 is an apocalyptic number.

It is an amenable number.

81713381 is a deficient number, since it is larger than the sum of its proper divisors (1).

81713381 is an equidigital number, since it uses as much as digits as its factorization.

81713381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 81713381 is about 9039.5453978616. The cubic root of 81713381 is about 433.9413743572.

The spelling of 81713381 in words is "eighty-one million, seven hundred thirteen thousand, three hundred eighty-one".