55621861 has 2 divisors, whose sum is σ = 55621862. Its totient is φ = 55621860.

The previous prime is 55621847. The next prime is 55621879. The reversal of 55621861 is 16812655.

It is a happy number.

55621861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54671236 + 950625 = 7394^2 + 975^2 .

It is a cyclic number.

It is not a de Polignac number, because 55621861 - 2⁵ = 55621829 is a prime.

It is a super-2 number, since 2×55621861² = 6187582842206642, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55621801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27810930 + 27810931.

It is an arithmetic number, because the mean of its divisors is an integer number (27810931).

Almost surely, 2^55621861 is an apocalyptic number.

It is an amenable number.

55621861 is a deficient number, since it is larger than the sum of its proper divisors (1).

55621861 is an equidigital number, since it uses as much as digits as its factorization.

55621861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 34.

The square root of 55621861 is about 7458.0065030811. The cubic root of 55621861 is about 381.7231554061.

The spelling of 55621861 in words is "fifty-five million, six hundred twenty-one thousand, eight hundred sixty-one".