81556266 has 16 divisors (see below), whose sum is σ = 177941088. Its totient is φ = 24714000.

The previous prime is 81556261. The next prime is 81556273. The reversal of 81556266 is 66265518.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81556261) 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, 617785 + ... + 617916.

It is an arithmetic number, because the mean of its divisors is an integer number (11121318).

Almost surely, 2^81556266 is an apocalyptic number.

81556266 is an abundant number, since it is smaller than the sum of its proper divisors (96384822).

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

81556266 is a wasteful number, since it uses less digits than its factorization.

81556266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1235717.

The product of its digits is 86400, while the sum is 39.

The square root of 81556266 is about 9030.8507904848. The cubic root of 81556266 is about 433.6630745979.

The spelling of 81556266 in words is "eighty-one million, five hundred fifty-six thousand, two hundred sixty-six".