81557868 has 24 divisors (see below), whose sum is σ = 217487872. Its totient is φ = 23302224.

The previous prime is 81557867. The next prime is 81557887. The reversal of 81557868 is 86875518.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81557867) 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, 485380 + ... + 485547.

Almost surely, 2^81557868 is an apocalyptic number.

It is an amenable number.

81557868 is an abundant number, since it is smaller than the sum of its proper divisors (135930004).

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

81557868 is a wasteful number, since it uses less digits than its factorization.

81557868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 970941 (or 970939 counting only the distinct ones).

The product of its digits is 537600, while the sum is 48.

The square root of 81557868 is about 9030.9394860114. The cubic root of 81557868 is about 433.6659140433.

The spelling of 81557868 in words is "eighty-one million, five hundred fifty-seven thousand, eight hundred sixty-eight".