81550656 has 168 divisors, whose sum is σ = 260408928. Its totient is φ = 24192000.

The previous prime is 81550633. The next prime is 81550657. The reversal of 81550656 is 65605518.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81550656.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81550657) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 386391 + ... + 386601.

Almost surely, 2^81550656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81550656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130204464).

81550656 is an abundant number, since it is smaller than the sum of its proper divisors (178858272).

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

81550656 is a wasteful number, since it uses less digits than its factorization.

81550656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301 (or 288 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 36.

The square root of 81550656 is about 9030.5401831784. The cubic root of 81550656 is about 433.6531309285.

The spelling of 81550656 in words is "eighty-one million, five hundred fifty thousand, six hundred fifty-six".