81408190646 has 16 divisors (see below), whose sum is σ = 126154074240. Its totient is φ = 39358971840.

The previous prime is 81408190637. The next prime is 81408190687. The reversal of 81408190646 is 64609180418.

It is a self number, because there is not a number n which added to its sum of digits gives 81408190646.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 457991 + ... + 610386.

It is an arithmetic number, because the mean of its divisors is an integer number (7884629640).

Almost surely, 2^81408190646 is an apocalyptic number.

81408190646 is a deficient number, since it is larger than the sum of its proper divisors (44745883594).

81408190646 is a wasteful number, since it uses less digits than its factorization.

81408190646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1069639.

The product of its (nonzero) digits is 331776, while the sum is 47.

The spelling of 81408190646 in words is "eighty-one billion, four hundred eight million, one hundred ninety thousand, six hundred forty-six".