81911425 has 6 divisors (see below), whose sum is σ = 101570198. Its totient is φ = 65529120.

The previous prime is 81911407. The next prime is 81911437. The reversal of 81911425 is 52411918.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 4330561 + 77580864 = 2081^2 + 8808^2 .

It is not a de Polignac number, because 81911425 - 2¹³ = 81903233 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 1638204 + ... + 1638253.

Almost surely, 2^81911425 is an apocalyptic number.

It is an amenable number.

81911425 is a deficient number, since it is larger than the sum of its proper divisors (19658773).

81911425 is a wasteful number, since it uses less digits than its factorization.

81911425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3276467 (or 3276462 counting only the distinct ones).

The product of its digits is 2880, while the sum is 31.

The square root of 81911425 is about 9050.4930804901. The cubic root of 81911425 is about 434.2916643953.

The spelling of 81911425 in words is "eighty-one million, nine hundred eleven thousand, four hundred twenty-five".