81423556 has 6 divisors (see below), whose sum is σ = 142491230. Its totient is φ = 40711776.

The previous prime is 81423547. The next prime is 81423571. The reversal of 81423556 is 65532418.

It can be written as a sum of positive squares in only one way, i.e., 75342400 + 6081156 = 8680^2 + 2466^2 .

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 as a sum of consecutive naturals, namely, 10177941 + ... + 10177948.

Almost surely, 2^81423556 is an apocalyptic number.

It is an amenable number.

81423556 is a deficient number, since it is larger than the sum of its proper divisors (61067674).

81423556 is a wasteful number, since it uses less digits than its factorization.

81423556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20355893 (or 20355891 counting only the distinct ones).

The product of its digits is 28800, while the sum is 34.

The square root of 81423556 is about 9023.5002077908. The cubic root of 81423556 is about 433.4277251310.

The spelling of 81423556 in words is "eighty-one million, four hundred twenty-three thousand, five hundred fifty-six".