81646000 has 40 divisors (see below), whose sum is σ = 197424864. Its totient is φ = 32657600.

The previous prime is 81645997. The next prime is 81646009. The reversal of 81646000 is 64618.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (81646009) 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, 18412 + ... + 22411.

Almost surely, 2^81646000 is an apocalyptic number.

81646000 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81646000 is an abundant number, since it is smaller than the sum of its proper divisors (115778864).

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

81646000 is a wasteful number, since it uses less digits than its factorization.

81646000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40846 (or 40830 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 81646000 is about 9035.8176165746. The cubic root of 81646000 is about 433.8220652794.

The spelling of 81646000 in words is "eighty-one million, six hundred forty-six thousand".