6420555181 has 2 divisors, whose sum is σ = 6420555182. Its totient is φ = 6420555180.

The previous prime is 6420555149. The next prime is 6420555233. The reversal of 6420555181 is 1815550246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4824552681 + 1596002500 = 69459^2 + 39950^2 .

It is a cyclic number.

It is not a de Polignac number, because 6420555181 - 2⁵ = 6420555149 is a prime.

It is a super-2 number, since 2×6420555181² = 82447057664531885522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6420555181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6420555131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3210277590 + 3210277591.

It is an arithmetic number, because the mean of its divisors is an integer number (3210277591).

Almost surely, 2^6420555181 is an apocalyptic number.

It is an amenable number.

6420555181 is a deficient number, since it is larger than the sum of its proper divisors (1).

6420555181 is an equidigital number, since it uses as much as digits as its factorization.

6420555181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48000, while the sum is 37.

The square root of 6420555181 is about 80128.3668933793. The cubic root of 6420555181 is about 1858.6210904784.

It can be divided in two parts, 6420555 and 181, that added together give a triangular number (6420736 = T₃₅₈₃).

The spelling of 6420555181 in words is "six billion, four hundred twenty million, five hundred fifty-five thousand, one hundred eighty-one".