81557086 has 16 divisors (see below), whose sum is σ = 131940144. Its totient is φ = 37586304.

The previous prime is 81557083. The next prime is 81557107. The reversal of 81557086 is 68075518.

It is a super-2 number, since 2×81557086² = 13303116553622792, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81557081) 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, 19606 + ... + 23398.

It is an arithmetic number, because the mean of its divisors is an integer number (8246259).

Almost surely, 2^81557086 is an apocalyptic number.

81557086 is a deficient number, since it is larger than the sum of its proper divisors (50383058).

81557086 is a wasteful number, since it uses less digits than its factorization.

81557086 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4635.

The product of its (nonzero) digits is 67200, while the sum is 40.

The square root of 81557086 is about 9030.8961903014. The cubic root of 81557086 is about 433.6645280015.

The spelling of 81557086 in words is "eighty-one million, five hundred fifty-seven thousand, eighty-six".