81084421 has 4 divisors (see below), whose sum is σ = 88455744. Its totient is φ = 73713100.

The previous prime is 81084413. The next prime is 81084431. The reversal of 81084421 is 12448018.

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 81084421 - 2³ = 81084413 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81084421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81084431) 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, 3685645 + ... + 3685666.

It is an arithmetic number, because the mean of its divisors is an integer number (22113936).

Almost surely, 2^81084421 is an apocalyptic number.

It is an amenable number.

81084421 is a deficient number, since it is larger than the sum of its proper divisors (7371323).

81084421 is a wasteful number, since it uses less digits than its factorization.

81084421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7371322.

The product of its (nonzero) digits is 2048, while the sum is 28.

The square root of 81084421 is about 9004.6888341575. The cubic root of 81084421 is about 432.8251351366.

The spelling of 81084421 in words is "eighty-one million, eighty-four thousand, four hundred twenty-one".