816642 has 30 divisors (see below), whose sum is σ = 1856019. Its totient is φ = 268380.

The previous prime is 816593. The next prime is 816649. The reversal of 816642 is 246618.

816642 is a `hidden beast` number, since 8 + 16 + 642 = 666.

It can be written as a sum of positive squares in only one way, i.e., 408321 + 408321 = 639^2 + 639^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=639.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (816649) by changing a digit.

816642 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 11467 + ... + 11537.

2⁸¹⁶⁶⁴² is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 816642

816642 is an abundant number, since it is smaller than the sum of its proper divisors (1039377).

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

816642 is an equidigital number, since it uses as much as digits as its factorization.

816642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156 (or 76 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 816642 is about 903.6824663564. The cubic root of 816642 is about 93.4710749651.

The spelling of 816642 in words is "eight hundred sixteen thousand, six hundred forty-two".