81876813 has 4 divisors (see below), whose sum is σ = 109169088. Its totient is φ = 54584540.

The previous prime is 81876791. The next prime is 81876829. The reversal of 81876813 is 31867818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81876813 - 2¹⁰ = 81875789 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81876013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13646133 + ... + 13646138.

It is an arithmetic number, because the mean of its divisors is an integer number (27292272).

Almost surely, 2^81876813 is an apocalyptic number.

It is an amenable number.

81876813 is a deficient number, since it is larger than the sum of its proper divisors (27292275).

81876813 is a wasteful number, since it uses less digits than its factorization.

81876813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27292274.

The product of its digits is 64512, while the sum is 42.

The square root of 81876813 is about 9048.5807174385. The cubic root of 81876813 is about 434.2304852178.

The spelling of 81876813 in words is "eighty-one million, eight hundred seventy-six thousand, eight hundred thirteen".