55321781 has 2 divisors, whose sum is σ = 55321782. Its totient is φ = 55321780.

The previous prime is 55321769. The next prime is 55321793. The reversal of 55321781 is 18712355.

It is a balanced prime because it is at equal distance from previous prime (55321769) and next prime (55321793).

It can be written as a sum of positive squares in only one way, i.e., 45024100 + 10297681 = 6710^2 + 3209^2 .

It is a cyclic number.

It is not a de Polignac number, because 55321781 - 2²² = 51127477 is a prime.

It is a super-2 number, since 2×55321781² = 6120998906023922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55321181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27660890 + 27660891.

It is an arithmetic number, because the mean of its divisors is an integer number (27660891).

Almost surely, 2^55321781 is an apocalyptic number.

It is an amenable number.

55321781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55321781 is an equidigital number, since it uses as much as digits as its factorization.

55321781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8400, while the sum is 32.

The square root of 55321781 is about 7437.8613189545. The cubic root of 55321781 is about 381.0354515869.

The spelling of 55321781 in words is "fifty-five million, three hundred twenty-one thousand, seven hundred eighty-one".