81558420 has 24 divisors (see below), whose sum is σ = 228363744. Its totient is φ = 21748896.

The previous prime is 81558413. The next prime is 81558439. The reversal of 81558420 is 2485518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 679594 + ... + 679713.

It is an arithmetic number, because the mean of its divisors is an integer number (9515156).

Almost surely, 2^81558420 is an apocalyptic number.

It is an amenable number.

81558420 is an abundant number, since it is smaller than the sum of its proper divisors (146805324).

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

81558420 is a wasteful number, since it uses less digits than its factorization.

81558420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1359319 (or 1359317 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 33.

The square root of 81558420 is about 9030.9700475641. The cubic root of 81558420 is about 433.6668924204. Note that the first 3 decimals are identical.

The spelling of 81558420 in words is "eighty-one million, five hundred fifty-eight thousand, four hundred twenty".