81557258 has 8 divisors (see below), whose sum is σ = 122609700. Its totient is φ = 40687360.

The previous prime is 81557257. The next prime is 81557297. The reversal of 81557258 is 85275518.

It can be written as a sum of positive squares in 2 ways, for example, as 80227849 + 1329409 = 8957^2 + 1153^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81557257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44513 + ... + 46308.

Almost surely, 2^81557258 is an apocalyptic number.

81557258 is a deficient number, since it is larger than the sum of its proper divisors (41052442).

81557258 is a wasteful number, since it uses less digits than its factorization.

81557258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91272.

The product of its digits is 112000, while the sum is 41.

The square root of 81557258 is about 9030.9057131608. The cubic root of 81557258 is about 433.6648328606.

The spelling of 81557258 in words is "eighty-one million, five hundred fifty-seven thousand, two hundred fifty-eight".