81609224 has 16 divisors (see below), whose sum is σ = 153694800. Its totient is φ = 40623952.

The previous prime is 81609223. The next prime is 81609271. The reversal of 81609224 is 42290618.

It is not an unprimeable number, because it can be changed into a prime (81609223) 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, 20654 + ... + 24285.

It is an arithmetic number, because the mean of its divisors is an integer number (9605925).

Almost surely, 2^81609224 is an apocalyptic number.

It is an amenable number.

81609224 is a deficient number, since it is larger than the sum of its proper divisors (72085576).

81609224 is a wasteful number, since it uses less digits than its factorization.

81609224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45172 (or 45168 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 81609224 is about 9033.7823750631. The cubic root of 81609224 is about 433.7569196658.

The spelling of 81609224 in words is "eighty-one million, six hundred nine thousand, two hundred twenty-four".