81555408 has 60 divisors (see below), whose sum is σ = 248995968. Its totient is φ = 24713280.

The previous prime is 81555407. The next prime is 81555427. The reversal of 81555408 is 80455518.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81555403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24160 + ... + 27327.

Almost surely, 2^81555408 is an apocalyptic number.

81555408 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

81555408 is an abundant number, since it is smaller than the sum of its proper divisors (167440560).

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

81555408 is a wasteful number, since it uses less digits than its factorization.

81555408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51512 (or 51503 counting only the distinct ones).

The product of its (nonzero) digits is 32000, while the sum is 36.

The square root of 81555408 is about 9030.8032865299. The cubic root of 81555408 is about 433.6615538309.

The spelling of 81555408 in words is "eighty-one million, five hundred fifty-five thousand, four hundred eight".