81035870221 has 2 divisors, whose sum is σ = 81035870222. Its totient is φ = 81035870220.

The previous prime is 81035870191. The next prime is 81035870233. The reversal of 81035870221 is 12207853018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41693147721 + 39342722500 = 204189^2 + 198350^2 .

It is a cyclic number.

It is not a de Polignac number, because 81035870221 - 2¹³ = 81035862029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81035870621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40517935110 + 40517935111.

It is an arithmetic number, because the mean of its divisors is an integer number (40517935111).

Almost surely, 2^81035870221 is an apocalyptic number.

It is an amenable number.

81035870221 is a deficient number, since it is larger than the sum of its proper divisors (1).

81035870221 is an equidigital number, since it uses as much as digits as its factorization.

81035870221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26880, while the sum is 37.

The spelling of 81035870221 in words is "eighty-one billion, thirty-five million, eight hundred seventy thousand, two hundred twenty-one".