81878893 has 2 divisors, whose sum is σ = 81878894. Its totient is φ = 81878892.

The previous prime is 81878887. The next prime is 81878911. The reversal of 81878893 is 39887818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78180964 + 3697929 = 8842^2 + 1923^2 .

It is a cyclic number.

It is not a de Polignac number, because 81878893 - 2¹⁷ = 81747821 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81878893.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81878813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40939446 + 40939447.

It is an arithmetic number, because the mean of its divisors is an integer number (40939447).

Almost surely, 2^81878893 is an apocalyptic number.

It is an amenable number.

81878893 is a deficient number, since it is larger than the sum of its proper divisors (1).

81878893 is an equidigital number, since it uses as much as digits as its factorization.

81878893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 774144, while the sum is 52.

The square root of 81878893 is about 9048.6956518605. The cubic root of 81878893 is about 434.2341622529.

The spelling of 81878893 in words is "eighty-one million, eight hundred seventy-eight thousand, eight hundred ninety-three".