55681921 has 4 divisors (see below), whose sum is σ = 57478144. Its totient is φ = 53885700.

The previous prime is 55681907. The next prime is 55681933. The reversal of 55681921 is 12918655.

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 55681921 - 2⁵ = 55681889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55681721) 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 3 ways as a sum of consecutive naturals, for example, 898065 + ... + 898126.

It is an arithmetic number, because the mean of its divisors is an integer number (14369536).

Almost surely, 2^55681921 is an apocalyptic number.

It is an amenable number.

55681921 is a deficient number, since it is larger than the sum of its proper divisors (1796223).

55681921 is a wasteful number, since it uses less digits than its factorization.

55681921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1796222.

The product of its digits is 21600, while the sum is 37.

The square root of 55681921 is about 7462.0319618720. The cubic root of 55681921 is about 381.8604997606.

The spelling of 55681921 in words is "fifty-five million, six hundred eighty-one thousand, nine hundred twenty-one".