81564464 has 40 divisors (see below), whose sum is σ = 163418112. Its totient is φ = 39412800.

The previous prime is 81564451. The next prime is 81564467. The reversal of 81564464 is 46446518.

It is not an unprimeable number, because it can be changed into a prime (81564467) 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, 70289 + ... + 71439.

Almost surely, 2^81564464 is an apocalyptic number.

It is an amenable number.

81564464 is an abundant number, since it is smaller than the sum of its proper divisors (81853648).

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

81564464 is a wasteful number, since it uses less digits than its factorization.

81564464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1305 (or 1299 counting only the distinct ones).

The product of its digits is 92160, while the sum is 38.

The square root of 81564464 is about 9031.3046676546. The cubic root of 81564464 is about 433.6776046516.

It can be divided in two parts, 81564 and 464, that added together give a palindrome (82028).

The spelling of 81564464 in words is "eighty-one million, five hundred sixty-four thousand, four hundred sixty-four".