81000557 has 8 divisors (see below), whose sum is σ = 88623072. Its totient is φ = 73421200.

The previous prime is 81000541. The next prime is 81000571. The reversal of 81000557 is 75500018.

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

It is a cyclic number.

It is not a de Polignac number, because 81000557 - 2⁴ = 81000541 is a prime.

It is a super-2 number, since 2×81000557² = 13122180468620498, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81000587) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6794 + ... + 14427.

It is an arithmetic number, because the mean of its divisors is an integer number (11077884).

Almost surely, 2^81000557 is an apocalyptic number.

It is an amenable number.

81000557 is a deficient number, since it is larger than the sum of its proper divisors (7622515).

81000557 is a wasteful number, since it uses less digits than its factorization.

81000557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21579.

The product of its (nonzero) digits is 1400, while the sum is 26.

The square root of 81000557 is about 9000.0309443912. The cubic root of 81000557 is about 432.6758628591.

The spelling of 81000557 in words is "eighty-one million, five hundred fifty-seven", and thus it is an aban number.