81228990042 has 24 divisors (see below), whose sum is σ = 176139163200. Its totient is φ = 27054327240.

The previous prime is 81228990041. The next prime is 81228990061. The reversal of 81228990042 is 24009982218.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81228990042.

It is not an unprimeable number, because it can be changed into a prime (81228990041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1810792 + ... + 1855107.

It is an arithmetic number, because the mean of its divisors is an integer number (7339131800).

Almost surely, 2^81228990042 is an apocalyptic number.

81228990042 is an abundant number, since it is smaller than the sum of its proper divisors (94910173158).

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

81228990042 is a wasteful number, since it uses less digits than its factorization.

81228990042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3667138 (or 3667135 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The spelling of 81228990042 in words is "eighty-one billion, two hundred twenty-eight million, nine hundred ninety thousand, forty-two".