55213621 has 2 divisors, whose sum is σ = 55213622. Its totient is φ = 55213620.

The previous prime is 55213619. The next prime is 55213667. The reversal of 55213621 is 12631255.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45037521 + 10176100 = 6711^2 + 3190^2 .

It is a cyclic number.

It is not a de Polignac number, because 55213621 - 2¹ = 55213619 is a prime.

Together with 55213619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55213421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27606810 + 27606811.

It is an arithmetic number, because the mean of its divisors is an integer number (27606811).

Almost surely, 2^55213621 is an apocalyptic number.

It is an amenable number.

55213621 is a deficient number, since it is larger than the sum of its proper divisors (1).

55213621 is an equidigital number, since it uses as much as digits as its factorization.

55213621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1800, while the sum is 25.

The square root of 55213621 is about 7430.5868543474. The cubic root of 55213621 is about 380.7869678891.

Adding to 55213621 its reverse (12631255), we get a palindrome (67844876).

The spelling of 55213621 in words is "fifty-five million, two hundred thirteen thousand, six hundred twenty-one".