81886421 has 4 divisors (see below), whose sum is σ = 82134144. Its totient is φ = 81638700.

The previous prime is 81886403. The next prime is 81886451. The reversal of 81886421 is 12468818.

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 a de Polignac number, because none of the positive numbers 2^k-81886421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81886451) 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, 123365 + ... + 124026.

It is an arithmetic number, because the mean of its divisors is an integer number (20533536).

Almost surely, 2^81886421 is an apocalyptic number.

It is an amenable number.

81886421 is a deficient number, since it is larger than the sum of its proper divisors (247723).

81886421 is a wasteful number, since it uses less digits than its factorization.

81886421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247722.

The product of its digits is 24576, while the sum is 38.

The square root of 81886421 is about 9049.1116138547. Note that the first 3 decimals coincide. The cubic root of 81886421 is about 434.2474697712.

The spelling of 81886421 in words is "eighty-one million, eight hundred eighty-six thousand, four hundred twenty-one".