81355019 has 2 divisors, whose sum is σ = 81355020. Its totient is φ = 81355018.

The previous prime is 81355007. The next prime is 81355037. The reversal of 81355019 is 91055318.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81355019 - 2²⁴ = 64577803 is a prime.

It is a super-2 number, since 2×81355019² = 13237278232980722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81355619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40677509 + 40677510.

It is an arithmetic number, because the mean of its divisors is an integer number (40677510).

Almost surely, 2^81355019 is an apocalyptic number.

81355019 is a deficient number, since it is larger than the sum of its proper divisors (1).

81355019 is an equidigital number, since it uses as much as digits as its factorization.

81355019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5400, while the sum is 32.

The square root of 81355019 is about 9019.7017134715. The cubic root of 81355019 is about 433.3060806661.

The spelling of 81355019 in words is "eighty-one million, three hundred fifty-five thousand, nineteen".