55851821 has 2 divisors, whose sum is σ = 55851822. Its totient is φ = 55851820.

The previous prime is 55851793. The next prime is 55851827. The reversal of 55851821 is 12815855.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30096196 + 25755625 = 5486^2 + 5075^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55851821 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55851827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27925910 + 27925911.

It is an arithmetic number, because the mean of its divisors is an integer number (27925911).

Almost surely, 2^55851821 is an apocalyptic number.

It is an amenable number.

55851821 is a deficient number, since it is larger than the sum of its proper divisors (1).

55851821 is an equidigital number, since it uses as much as digits as its factorization.

55851821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16000, while the sum is 35.

The square root of 55851821 is about 7473.4075895805. The cubic root of 55851821 is about 382.2484905886.

The spelling of 55851821 in words is "fifty-five million, eight hundred fifty-one thousand, eight hundred twenty-one".