81606621546 has 24 divisors (see below), whose sum is σ = 176830879680. Its totient is φ = 27199663656.

The previous prime is 81606621541. The next prime is 81606621589. The reversal of 81606621546 is 64512660618.

81606621546 is a `hidden beast` number, since 8 + 16 + 0 + 6 + 621 + 5 + 4 + 6 = 666.

It is not an unprimeable number, because it can be changed into a prime (81606621541) 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 11 ways as a sum of consecutive naturals, for example, 8850 + ... + 404093.

It is an arithmetic number, because the mean of its divisors is an integer number (7367953320).

Almost surely, 2^81606621546 is an apocalyptic number.

81606621546 is an abundant number, since it is smaller than the sum of its proper divisors (95224258134).

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

81606621546 is a wasteful number, since it uses less digits than its factorization.

81606621546 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 423930 (or 423927 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 81606621546 in words is "eighty-one billion, six hundred six million, six hundred twenty-one thousand, five hundred forty-six".