81877813 has 2 divisors, whose sum is σ = 81877814. Its totient is φ = 81877812.

The previous prime is 81877793. The next prime is 81877823. The reversal of 81877813 is 31877818.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 75637809 + 6240004 = 8697^2 + 2498^2 .

It is a cyclic number.

It is not a de Polignac number, because 81877813 - 2¹³ = 81869621 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81877813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81877823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40938906 + 40938907.

It is an arithmetic number, because the mean of its divisors is an integer number (40938907).

Almost surely, 2^81877813 is an apocalyptic number.

It is an amenable number.

81877813 is a deficient number, since it is larger than the sum of its proper divisors (1).

81877813 is an equidigital number, since it uses as much as digits as its factorization.

81877813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75264, while the sum is 43.

The square root of 81877813 is about 9048.6359745544. The cubic root of 81877813 is about 434.2322530309.

The spelling of 81877813 in words is "eighty-one million, eight hundred seventy-seven thousand, eight hundred thirteen".