55613821 has 2 divisors, whose sum is σ = 55613822. Its totient is φ = 55613820.

The previous prime is 55613797. The next prime is 55613827. The reversal of 55613821 is 12831655.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38266596 + 17347225 = 6186^2 + 4165^2 .

It is a cyclic number.

It is not a de Polignac number, because 55613821 - 2⁹ = 55613309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55613827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27806910 + 27806911.

It is an arithmetic number, because the mean of its divisors is an integer number (27806911).

Almost surely, 2^55613821 is an apocalyptic number.

It is an amenable number.

55613821 is a deficient number, since it is larger than the sum of its proper divisors (1).

55613821 is an equidigital number, since it uses as much as digits as its factorization.

55613821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7200, while the sum is 31.

The square root of 55613821 is about 7457.4674655677. The cubic root of 55613821 is about 381.7047621460.

The spelling of 55613821 in words is "fifty-five million, six hundred thirteen thousand, eight hundred twenty-one".