81241187869 has 2 divisors, whose sum is σ = 81241187870. Its totient is φ = 81241187868.

The previous prime is 81241187837. The next prime is 81241187887. The reversal of 81241187869 is 96878114218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47104191225 + 34136996644 = 217035^2 + 184762^2 .

It is a cyclic number.

It is not a de Polignac number, because 81241187869 - 2⁵ = 81241187837 is a prime.

It is a super-2 number, since 2×81241187869² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81241187369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40620593934 + 40620593935.

It is an arithmetic number, because the mean of its divisors is an integer number (40620593935).

Almost surely, 2^81241187869 is an apocalyptic number.

It is an amenable number.

81241187869 is a deficient number, since it is larger than the sum of its proper divisors (1).

81241187869 is an equidigital number, since it uses as much as digits as its factorization.

81241187869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1548288, while the sum is 55.

The spelling of 81241187869 in words is "eighty-one billion, two hundred forty-one million, one hundred eighty-seven thousand, eight hundred sixty-nine".