55219781 has 2 divisors, whose sum is σ = 55219782. Its totient is φ = 55219780.

The previous prime is 55219763. The next prime is 55219807. The reversal of 55219781 is 18791255.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54626881 + 592900 = 7391^2 + 770^2 .

It is a cyclic number.

It is not a de Polignac number, because 55219781 - 2¹⁴ = 55203397 is a prime.

It is a super-2 number, since 2×55219781² = 6098448427375922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55219721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27609890 + 27609891.

It is an arithmetic number, because the mean of its divisors is an integer number (27609891).

Almost surely, 2^55219781 is an apocalyptic number.

It is an amenable number.

55219781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55219781 is an equidigital number, since it uses as much as digits as its factorization.

55219781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25200, while the sum is 38.

The square root of 55219781 is about 7431.0013457138. The cubic root of 55219781 is about 380.8011284076.

The spelling of 55219781 in words is "fifty-five million, two hundred nineteen thousand, seven hundred eighty-one".