81425885 has 4 divisors (see below), whose sum is σ = 97711068. Its totient is φ = 65140704.

The previous prime is 81425831. The next prime is 81425899. The reversal of 81425885 is 58852418.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58852418 = 2 ⋅29426209.

It can be written as a sum of positive squares in 2 ways, for example, as 40119556 + 41306329 = 6334^2 + 6427^2 .

It is a cyclic number.

It is not a de Polignac number, because 81425885 - 2⁶ = 81425821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8142584 + ... + 8142593.

It is an arithmetic number, because the mean of its divisors is an integer number (24427767).

Almost surely, 2^81425885 is an apocalyptic number.

It is an amenable number.

81425885 is a deficient number, since it is larger than the sum of its proper divisors (16285183).

81425885 is a wasteful number, since it uses less digits than its factorization.

81425885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16285182.

The product of its digits is 102400, while the sum is 41.

The square root of 81425885 is about 9023.6292587850. The cubic root of 81425885 is about 433.4318576106.

The spelling of 81425885 in words is "eighty-one million, four hundred twenty-five thousand, eight hundred eighty-five".