81639554 has 8 divisors (see below), whose sum is σ = 126409728. Its totient is φ = 39502980.

The previous prime is 81639527. The next prime is 81639587. The reversal of 81639554 is 45593618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 658322 + ... + 658445.

It is an arithmetic number, because the mean of its divisors is an integer number (15801216).

Almost surely, 2^81639554 is an apocalyptic number.

81639554 is a deficient number, since it is larger than the sum of its proper divisors (44770174).

81639554 is a wasteful number, since it uses less digits than its factorization.

81639554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316800.

The product of its digits is 129600, while the sum is 41.

The square root of 81639554 is about 9035.4609179610. The cubic root of 81639554 is about 433.8106481427.

The spelling of 81639554 in words is "eighty-one million, six hundred thirty-nine thousand, five hundred fifty-four".