55721329 has 2 divisors, whose sum is σ = 55721330. Its totient is φ = 55721328.

The previous prime is 55721293. The next prime is 55721363. The reversal of 55721329 is 92312755.

Together with previous prime (55721293) it forms an Ormiston pair, because they use the same digits, order apart.

It is an a-pointer prime, because the next prime (55721363) can be obtained adding 55721329 to its sum of digits (34).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 35426304 + 20295025 = 5952^2 + 4505^2 .

It is a cyclic number.

It is not a de Polignac number, because 55721329 - 2⁷ = 55721201 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 55721294 and 55721303.

It is not a weakly prime, because it can be changed into another prime (55721399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27860664 + 27860665.

It is an arithmetic number, because the mean of its divisors is an integer number (27860665).

Almost surely, 2^55721329 is an apocalyptic number.

It is an amenable number.

55721329 is a deficient number, since it is larger than the sum of its proper divisors (1).

55721329 is an equidigital number, since it uses as much as digits as its factorization.

55721329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18900, while the sum is 34.

The square root of 55721329 is about 7464.6720624553. The cubic root of 55721329 is about 381.9505637623.

The spelling of 55721329 in words is "fifty-five million, seven hundred twenty-one thousand, three hundred twenty-nine".