81603541 has 2 divisors, whose sum is σ = 81603542. Its totient is φ = 81603540.

The previous prime is 81603497. The next prime is 81603559. The reversal of 81603541 is 14530618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68310225 + 13293316 = 8265^2 + 3646^2 .

It is a cyclic number.

It is not a de Polignac number, because 81603541 - 2⁹ = 81603029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81603341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40801770 + 40801771.

It is an arithmetic number, because the mean of its divisors is an integer number (40801771).

Almost surely, 2^81603541 is an apocalyptic number.

It is an amenable number.

81603541 is a deficient number, since it is larger than the sum of its proper divisors (1).

81603541 is an equidigital number, since it uses as much as digits as its factorization.

81603541 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 81603541 is about 9033.4678280271. The cubic root of 81603541 is about 433.7468509600.

The spelling of 81603541 in words is "eighty-one million, six hundred three thousand, five hundred forty-one".