81084645 has 40 divisors (see below), whose sum is σ = 153914904. Its totient is φ = 40697856.

The previous prime is 81084629. The next prime is 81084709. The reversal of 81084645 is 54648018.

81084645 is a `hidden beast` number, since 8 + 1 + 0 + 8 + 4 + 645 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 23794884 + 57289761 = 4878^2 + 7569^2 .

It is not a de Polignac number, because 81084645 - 2⁴ = 81084629 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 997 + ... + 12773.

Almost surely, 2^81084645 is an apocalyptic number.

81084645 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81084645 is a deficient number, since it is larger than the sum of its proper divisors (72830259).

81084645 is a wasteful number, since it uses less digits than its factorization.

81084645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11811 (or 11802 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 36.

The square root of 81084645 is about 9004.7012721134. The cubic root of 81084645 is about 432.8255337037.

The spelling of 81084645 in words is "eighty-one million, eighty-four thousand, six hundred forty-five".