81629890578 has 12 divisors (see below), whose sum is σ = 176864762958. Its totient is φ = 27209963520.

The previous prime is 81629890543. The next prime is 81629890579. The reversal of 81629890578 is 87509892618.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 78224817969 + 3405072609 = 279687^2 + 58353^2 .

It is not an unprimeable number, because it can be changed into a prime (81629890579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2267496943 + ... + 2267496978.

Almost surely, 2^81629890578 is an apocalyptic number.

81629890578 is an abundant number, since it is smaller than the sum of its proper divisors (95234872380).

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

81629890578 is a wasteful number, since it uses less digits than its factorization.

81629890578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4534993929 (or 4534993926 counting only the distinct ones).

The product of its (nonzero) digits is 17418240, while the sum is 63.

The spelling of 81629890578 in words is "eighty-one billion, six hundred twenty-nine million, eight hundred ninety thousand, five hundred seventy-eight".