81633320 has 32 divisors (see below), whose sum is σ = 194481000. Its totient is φ = 30732288.

The previous prime is 81633319. The next prime is 81633373. The reversal of 81633320 is 2333618.

It can be written as a sum of positive squares in 4 ways, for example, as 81613156 + 20164 = 9034^2 + 142^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81633320.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 59345 + ... + 60704.

Almost surely, 2^81633320 is an apocalyptic number.

It is an amenable number.

81633320 is an abundant number, since it is smaller than the sum of its proper divisors (112847680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81633320 is a wasteful number, since it uses less digits than its factorization.

81633320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120077 (or 120073 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 81633320 is about 9035.1159372750. The cubic root of 81633320 is about 433.7996059282.

Adding to 81633320 its reverse (2333618), we get a palindrome (83966938).

The spelling of 81633320 in words is "eighty-one million, six hundred thirty-three thousand, three hundred twenty".