55821281 has 4 divisors (see below), whose sum is σ = 55836612. Its totient is φ = 55805952.

The previous prime is 55821277. The next prime is 55821287. The reversal of 55821281 is 18212855.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18212855 = 5 ⋅3642571.

It can be written as a sum of positive squares in 2 ways, for example, as 2531281 + 53290000 = 1591^2 + 7300^2 .

It is a cyclic number.

It is not a de Polignac number, because 55821281 - 2² = 55821277 is a prime.

It is a super-2 number, since 2×55821281² = 6232030824961922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55821287) 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, 1265 + ... + 10641.

It is an arithmetic number, because the mean of its divisors is an integer number (13959153).

Almost surely, 2^55821281 is an apocalyptic number.

It is an amenable number.

55821281 is a deficient number, since it is larger than the sum of its proper divisors (15331).

55821281 is an equidigital number, since it uses as much as digits as its factorization.

55821281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15330.

The product of its digits is 6400, while the sum is 32.

The square root of 55821281 is about 7471.3640655505. The cubic root of 55821281 is about 382.1788062159.

The spelling of 55821281 in words is "fifty-five million, eight hundred twenty-one thousand, two hundred eighty-one".