81904461 has 4 divisors (see below), whose sum is σ = 109205952. Its totient is φ = 54602972.

The previous prime is 81904447. The next prime is 81904463. The reversal of 81904461 is 16440918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81904461 - 2⁶ = 81904397 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81904463) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 13650741 + ... + 13650746.

It is an arithmetic number, because the mean of its divisors is an integer number (27301488).

Almost surely, 2^81904461 is an apocalyptic number.

It is an amenable number.

81904461 is a deficient number, since it is larger than the sum of its proper divisors (27301491).

81904461 is a wasteful number, since it uses less digits than its factorization.

81904461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27301490.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 81904461 is about 9050.1083418929. The cubic root of 81904461 is about 434.2793564139.

The spelling of 81904461 in words is "eighty-one million, nine hundred four thousand, four hundred sixty-one".