81606402 has 48 divisors (see below), whose sum is σ = 181014912. Its totient is φ = 26563680.

The previous prime is 81606401. The next prime is 81606403. The reversal of 81606402 is 20460618.

81606402 is a `hidden beast` number, since 8 + 16 + 0 + 640 + 2 = 666.

It is an interprime number because it is at equal distance from previous prime (81606401) and next prime (81606403).

It is not an unprimeable number, because it can be changed into a prime (81606401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 189127 + ... + 189557.

It is an arithmetic number, because the mean of its divisors is an integer number (3771144).

Almost surely, 2^81606402 is an apocalyptic number.

81606402 is an abundant number, since it is smaller than the sum of its proper divisors (99408510).

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

81606402 is a wasteful number, since it uses less digits than its factorization.

81606402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 663 (or 660 counting only the distinct ones).

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

The square root of 81606402 is about 9033.6261822150. The cubic root of 81606402 is about 433.7519199200.

The spelling of 81606402 in words is "eighty-one million, six hundred six thousand, four hundred two".