55821021 has 8 divisors (see below), whose sum is σ = 75689760. Its totient is φ = 36583152.

The previous prime is 55821011. The next prime is 55821043. The reversal of 55821021 is 12012855.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 55821021 - 2⁶ = 55820957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 55820982 and 55821000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55821011) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 157510 + ... + 157863.

It is an arithmetic number, because the mean of its divisors is an integer number (9461220).

Almost surely, 2^55821021 is an apocalyptic number.

It is an amenable number.

55821021 is a deficient number, since it is larger than the sum of its proper divisors (19868739).

55821021 is a wasteful number, since it uses less digits than its factorization.

55821021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315435.

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 55821021 is about 7471.3466657625. The cubic root of 55821021 is about 382.1782128541.

Adding to 55821021 its reverse (12012855), we get a palindrome (67833876).

The spelling of 55821021 in words is "fifty-five million, eight hundred twenty-one thousand, twenty-one".