81560664 has 24 divisors (see below), whose sum is σ = 220893660. Its totient is φ = 27186864.

The previous prime is 81560657. The next prime is 81560669. The reversal of 81560664 is 46606518.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81560669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 566322 + ... + 566465.

Almost surely, 2^81560664 is an apocalyptic number.

It is an amenable number.

81560664 is an abundant number, since it is smaller than the sum of its proper divisors (139332996).

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

81560664 is a wasteful number, since it uses less digits than its factorization.

81560664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1132799 (or 1132792 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 81560664 is about 9031.0942858548. The cubic root of 81560664 is about 433.6708696904.

The spelling of 81560664 in words is "eighty-one million, five hundred sixty thousand, six hundred sixty-four".