81907019 has 2 divisors, whose sum is σ = 81907020. Its totient is φ = 81907018.

The previous prime is 81907013. The next prime is 81907051. The reversal of 81907019 is 91070918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81907019 - 2²⁴ = 65129803 is a prime.

It is a super-2 number, since 2×81907019² = 13417519522932722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81907019.

It is not a weakly prime, because it can be changed into another prime (81907013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40953509 + 40953510.

It is an arithmetic number, because the mean of its divisors is an integer number (40953510).

Almost surely, 2^81907019 is an apocalyptic number.

81907019 is a deficient number, since it is larger than the sum of its proper divisors (1).

81907019 is an equidigital number, since it uses as much as digits as its factorization.

81907019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 81907019 is about 9050.2496650645. The cubic root of 81907019 is about 434.2838774336.

The spelling of 81907019 in words is "eighty-one million, nine hundred seven thousand, nineteen".