81309456 has 60 divisors (see below), whose sum is σ = 230329008. Its totient is φ = 26772672.

The previous prime is 81309433. The next prime is 81309467. The reversal of 81309456 is 65490318.

It is a super-2 number, since 2×81309456² = 13222455270031872, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81309456.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8551 + ... + 15353.

Almost surely, 2^81309456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81309456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115164504).

81309456 is an abundant number, since it is smaller than the sum of its proper divisors (149019552).

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

81309456 is a wasteful number, since it uses less digits than its factorization.

81309456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6900 (or 6891 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The square root of 81309456 is about 9017.1756110214. The cubic root of 81309456 is about 433.2251743209.

The spelling of 81309456 in words is "eighty-one million, three hundred nine thousand, four hundred fifty-six".