81306432 has 42 divisors (see below), whose sum is σ = 233051858. Its totient is φ = 27101952.

The previous prime is 81306413. The next prime is 81306437. The reversal of 81306432 is 23460318.

It is a happy number.

81306432 is a `hidden beast` number, since 8 + 13 + 0 + 643 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 70963776 + 10342656 = 8424^2 + 3216^2 .

It is a super-2 number, since 2×81306432² = 13221471769141248, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81306396 and 81306405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81306437) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 70003 + ... + 71154.

Almost surely, 2^81306432 is an apocalyptic number.

It is an amenable number.

81306432 is an abundant number, since it is smaller than the sum of its proper divisors (151745426).

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

81306432 is a wasteful number, since it uses less digits than its factorization.

81306432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141175 (or 141162 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 81306432 is about 9017.0079294631. The cubic root of 81306432 is about 433.2198035263.

The spelling of 81306432 in words is "eighty-one million, three hundred six thousand, four hundred thirty-two".