55906821 has 16 divisors (see below), whose sum is σ = 84846720. Its totient is φ = 36361440.

The previous prime is 55906819. The next prime is 55906847. The reversal of 55906821 is 12860955.

It is a happy number.

55906821 is a `hidden beast` number, since 5 + 590 + 68 + 2 + 1 = 666.

It is not a de Polignac number, because 55906821 - 2¹ = 55906819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55906021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24145 + ... + 26358.

It is an arithmetic number, because the mean of its divisors is an integer number (5302920).

Almost surely, 2^55906821 is an apocalyptic number.

It is an amenable number.

55906821 is a deficient number, since it is larger than the sum of its proper divisors (28939899).

55906821 is a wasteful number, since it uses less digits than its factorization.

55906821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50553 (or 50547 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 55906821 is about 7477.0863977889. The cubic root of 55906821 is about 382.3739223075.

The spelling of 55906821 in words is "fifty-five million, nine hundred six thousand, eight hundred twenty-one".