55421921 has 4 divisors (see below), whose sum is σ = 58682052. Its totient is φ = 52161792.

The previous prime is 55421909. The next prime is 55421923. The reversal of 55421921 is 12912455.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12912455 = 5 ⋅2582491.

It can be written as a sum of positive squares in 2 ways, for example, as 25391521 + 30030400 = 5039^2 + 5480^2 .

It is a cyclic number.

It is not a de Polignac number, because 55421921 - 2⁶ = 55421857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55421923) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1630040 + ... + 1630073.

It is an arithmetic number, because the mean of its divisors is an integer number (14670513).

Almost surely, 2^55421921 is an apocalyptic number.

It is an amenable number.

55421921 is a deficient number, since it is larger than the sum of its proper divisors (3260131).

55421921 is a wasteful number, since it uses less digits than its factorization.

55421921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3260130.

The product of its digits is 3600, while the sum is 29.

The square root of 55421921 is about 7444.5900491565. The cubic root of 55421921 is about 381.2652217877.

The spelling of 55421921 in words is "fifty-five million, four hundred twenty-one thousand, nine hundred twenty-one".