81646928 has 60 divisors (see below), whose sum is σ = 175590324. Its totient is φ = 36748800.

The previous prime is 81646927. The next prime is 81646969. The reversal of 81646928 is 82964618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6512704 + 75134224 = 2552^2 + 8668^2 .

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81646921) 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, 350300 + ... + 350532.

Almost surely, 2^81646928 is an apocalyptic number.

81646928 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81646928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87795162).

81646928 is an abundant number, since it is smaller than the sum of its proper divisors (93943396).

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

81646928 is a wasteful number, since it uses less digits than its factorization.

81646928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444 (or 427 counting only the distinct ones).

The product of its digits is 165888, while the sum is 44.

The square root of 81646928 is about 9035.8689676201. The cubic root of 81646928 is about 433.8237089009.

The spelling of 81646928 in words is "eighty-one million, six hundred forty-six thousand, nine hundred twenty-eight".