55720730621 has 2 divisors, whose sum is σ = 55720730622. Its totient is φ = 55720730620.

The previous prime is 55720730579. The next prime is 55720730647. The reversal of 55720730621 is 12603702755.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49423514596 + 6297216025 = 222314^2 + 79355^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55720730621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55720730521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27860365310 + 27860365311.

It is an arithmetic number, because the mean of its divisors is an integer number (27860365311).

Almost surely, 2^55720730621 is an apocalyptic number.

It is an amenable number.

55720730621 is a deficient number, since it is larger than the sum of its proper divisors (1).

55720730621 is an equidigital number, since it uses as much as digits as its factorization.

55720730621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 88200, while the sum is 38.

The spelling of 55720730621 in words is "fifty-five billion, seven hundred twenty million, seven hundred thirty thousand, six hundred twenty-one".