81654321 has 32 divisors (see below), whose sum is σ = 127733760. Its totient is φ = 45437184.

The previous prime is 81654319. The next prime is 81654323. The reversal of 81654321 is 12345618.

It is an interprime number because it is at equal distance from previous prime (81654319) and next prime (81654323).

It is not a de Polignac number, because 81654321 - 2¹ = 81654319 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (81654323) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 137401 + ... + 137993.

It is an arithmetic number, because the mean of its divisors is an integer number (3991680).

Almost surely, 2^81654321 is an apocalyptic number.

It is an amenable number.

81654321 is a deficient number, since it is larger than the sum of its proper divisors (46079439).

81654321 is a wasteful number, since it uses less digits than its factorization.

81654321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 765.

The product of its digits is 5760, while the sum is 30.

The square root of 81654321 is about 9036.2780501709. The cubic root of 81654321 is about 433.8368025222.

Adding to 81654321 its reverse (12345618), we get a palindrome (93999939).

The spelling of 81654321 in words is "eighty-one million, six hundred fifty-four thousand, three hundred twenty-one".