81166645 has 16 divisors (see below), whose sum is σ = 112030848. Its totient is φ = 55298880.

The previous prime is 81166643. The next prime is 81166739. The reversal of 81166645 is 54666118.

It is not a de Polignac number, because 81166645 - 2¹ = 81166643 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81166643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1891 + ... + 12880.

It is an arithmetic number, because the mean of its divisors is an integer number (7001928).

Almost surely, 2^81166645 is an apocalyptic number.

It is an amenable number.

81166645 is a deficient number, since it is larger than the sum of its proper divisors (30864203).

81166645 is a wasteful number, since it uses less digits than its factorization.

81166645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14940.

The product of its digits is 34560, while the sum is 37.

The square root of 81166645 is about 9009.2532986924. The cubic root of 81166645 is about 432.9713884310.

The spelling of 81166645 in words is "eighty-one million, one hundred sixty-six thousand, six hundred forty-five".