81879181 has 4 divisors (see below), whose sum is σ = 83783392. Its totient is φ = 79974972.

The previous prime is 81879167. The next prime is 81879221. The reversal of 81879181 is 18197818.

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 81879181 - 2¹³ = 81870989 is a prime.

It is a super-2 number, since 2×81879181² = 13408400562461522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 1904167 = 81879181 / (8 + 1 + 8 + 7 + 9 + 1 + 8 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81879101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 952041 + ... + 952126.

It is an arithmetic number, because the mean of its divisors is an integer number (20945848).

Almost surely, 2^81879181 is an apocalyptic number.

It is an amenable number.

81879181 is a deficient number, since it is larger than the sum of its proper divisors (1904211).

81879181 is a wasteful number, since it uses less digits than its factorization.

81879181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1904210.

The product of its digits is 32256, while the sum is 43.

The square root of 81879181 is about 9048.7115657424. The cubic root of 81879181 is about 434.2346713760.

The spelling of 81879181 in words is "eighty-one million, eight hundred seventy-nine thousand, one hundred eighty-one".