81312364 has 36 divisors (see below), whose sum is σ = 167825784. Its totient is φ = 34364736.

The previous prime is 81312313. The next prime is 81312367. The reversal of 81312364 is 46321318.

It is a super-2 number, since 2×81312364² = 13223401078536992, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (81312367) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11467 + ... + 17149.

Almost surely, 2^81312364 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 81312364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83912892).

81312364 is an abundant number, since it is smaller than the sum of its proper divisors (86513420).

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

81312364 is a wasteful number, since it uses less digits than its factorization.

81312364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5774 (or 5765 counting only the distinct ones).

The product of its digits is 3456, while the sum is 28.

The square root of 81312364 is about 9017.3368574097. The cubic root of 81312364 is about 433.2303389674.

It can be divided in two parts, 81 and 312364, that added together give a triangular number (312445 = T₇₉₀).

The spelling of 81312364 in words is "eighty-one million, three hundred twelve thousand, three hundred sixty-four".