81564977 has 6 divisors (see below), whose sum is σ = 88322022. Its totient is φ = 75290592.

The previous prime is 81564943. The next prime is 81565007. The reversal of 81564977 is 77946518.

It can be written as a sum of positive squares in 3 ways, for example, as 5683456 + 75881521 = 2384^2 + 8711^2 .

It is not a de Polignac number, because 81564977 - 2¹² = 81560881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81564277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 241148 + ... + 241485.

It is an arithmetic number, because the mean of its divisors is an integer number (14720337).

Almost surely, 2^81564977 is an apocalyptic number.

It is an amenable number.

81564977 is a deficient number, since it is larger than the sum of its proper divisors (6757045).

81564977 is a wasteful number, since it uses less digits than its factorization.

81564977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482659 (or 482646 counting only the distinct ones).

The product of its digits is 423360, while the sum is 47.

The square root of 81564977 is about 9031.3330688221. Note that the first 3 decimals coincide. The cubic root of 81564977 is about 433.6785138553.

The spelling of 81564977 in words is "eighty-one million, five hundred sixty-four thousand, nine hundred seventy-seven".