81896409 has 24 divisors (see below), whose sum is σ = 136468800. Its totient is φ = 46356768.

The previous prime is 81896401. The next prime is 81896443. The reversal of 81896409 is 90469818.

It is not a de Polignac number, because 81896409 - 2³ = 81896401 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81896401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 667 + ... + 12815.

It is an arithmetic number, because the mean of its divisors is an integer number (5686200).

Almost surely, 2^81896409 is an apocalyptic number.

It is an amenable number.

81896409 is a deficient number, since it is larger than the sum of its proper divisors (54572391).

81896409 is a wasteful number, since it uses less digits than its factorization.

81896409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12269 (or 12266 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 81896409 is about 9049.6634744061. The cubic root of 81896409 is about 434.2651246618.

The spelling of 81896409 in words is "eighty-one million, eight hundred ninety-six thousand, four hundred nine".